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2
.gitignore vendored
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@ -1,2 +0,0 @@
.DS_Store
.idea/

3
README
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XX
Random experiments in Go.

87
arena/arena.go
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package arena
import (
"unsafe"
"git.brut.systems/judah/xx/mem"
)
// New returns a pointer to an Arena allocated value of type T.
// If allocation fails, New will panic.
//
// Note: Accessing the returned value after calling Reset is unsafe and may result in a fault.
func New[T any](arena Arena) *T {
ptr, err := arena(ACTION_ALLOC, mem.Sizeof[T](), mem.Alignof[T](), nil)
if err != nil {
panic(err)
}
return (*T)(ptr)
}
// MakeSlice creates an Arena allocated []T with the given capacity and length.
// If allocation fails, MakeSlice will panic.
//
// Note: Accessing the returned slice after calling Reset is unsafe and may result in a fault.
func MakeSlice[T any](arena Arena, len, cap int) []T {
ptr, err := arena(ACTION_ALLOC, mem.Sizeof[T]()*uintptr(len), mem.Alignof[T](), nil)
if err != nil {
panic(err)
}
return unsafe.Slice((*T)(ptr), cap)[:len]
}
// Reset restores an Arena to its initial state.
//
// Note: Accessing memory returned by an Arena after calling Reset is unsafe and may result in a fault.
func Reset(arena Arena) {
if _, err := arena(ACTION_RESET, 0, 0, nil); err != nil {
panic(err)
}
}
// Save returns the restorable state of an Arena.
// The returned value is internal to the particular Arena and should not be modified.
func Save(arena Arena) (watermark uintptr) {
if _, err := arena(ACTION_SAVE, 0, 0, &watermark); err != nil {
panic(err)
}
return
}
// Restore restores an Arena to a previously saved state.
func Restore(arena Arena, watermark uintptr) {
if _, err := arena(ACTION_RESTORE, 0, 0, &watermark); err != nil {
panic(err)
}
}
// Arena represents a memory allocator.
type Arena func(a Action, size, align uintptr, watermark *uintptr) (unsafe.Pointer, error)
// Action is a list of distinct events an Arena may respond to.
type Action int
const (
ACTION_ALLOC Action = iota
ACTION_RESET
ACTION_SAVE
ACTION_RESTORE
)
func (a Action) String() string {
switch a {
case ACTION_ALLOC:
return "ALLOC"
case ACTION_RESET:
return "RESET"
case ACTION_SAVE:
return "SAVE"
case ACTION_RESTORE:
return "RESTORE"
default:
panic("unreachable")
}
}

30
arena/arena_test.go
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@ -1,30 +0,0 @@
package arena_test
import (
"testing"
"git.brut.systems/judah/xx/arena"
"git.brut.systems/judah/xx/mem"
"git.brut.systems/judah/xx/testx"
)
func TestMakeSlice(t *testing.T) {
a := arena.Linear(1024 * mem.Kilobyte)
defer arena.Reset(a)
s := arena.MakeSlice[int](a, 99, 100)
testx.Expect(t, len(s) == 99, "len = %d, expected 99", len(s))
testx.Expect(t, cap(s) == 100, "cap = %d, expected 100", cap(s))
p := &s[0]
s[2] = 0xCAFE_DECAF
s = append(s, 2)
testx.Expect(t, p == &s[0], "p = %p, expected %p", p, &s[0])
p = &s[0]
s = append(s, 3) // cause a reallocation
testx.Expect(t, p != &s[0], "p = %p, expected %p", p, &s[0])
}

269
arena/arenas.go
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@ -1,269 +0,0 @@
package arena
import (
"errors"
"log"
"math/bits"
"runtime"
"sync"
"unsafe"
"git.brut.systems/judah/xx/mem"
)
// Linear is a simple bump allocator with a fixed amount of backing memory.
func Linear(capacity_in_bytes uintptr) Arena {
if capacity_in_bytes <= 0 {
panic("linear: capacity_in_bytes must be greater than zero")
}
var (
data = make([]byte, capacity_in_bytes)
offset uintptr
)
return func(a Action, size, align uintptr, watermark *uintptr) (unsafe.Pointer, error) {
switch a {
case ACTION_ALLOC:
aligned := mem.AlignForward(size, align)
if offset+aligned > capacity_in_bytes {
return nil, errors.New("linear: out of memory")
}
ptr := &data[offset]
offset += aligned
return unsafe.Pointer(ptr), nil
case ACTION_RESET:
clear(data)
offset = 0
case ACTION_SAVE:
if watermark == nil {
return nil, errors.New("linear: cannot save to nil watermark")
}
*watermark = offset
case ACTION_RESTORE:
if watermark == nil {
return nil, errors.New("linear: cannot restore nil watermark")
}
clear(data[*watermark:offset])
offset = *watermark
default:
panic("linear: unimplemented action - " + a.String())
}
return nil, nil
}
}
// Ring is an Arena that only allocates values of the given type.
// When capacity is exceeded, previous allocations will be reused to accommodate new ones
//
// Note: Allocating different types from the same Pool is unsafe and may cause memory corruption.
func Ring[T any](capacity uintptr) Arena {
if capacity <= 0 {
panic("pool: capacity must be greater than zero")
}
pointers := make([]T, 0, capacity)
return func(a Action, _, _ uintptr, watermark *uintptr) (unsafe.Pointer, error) {
switch a {
case ACTION_ALLOC:
if len(pointers) == cap(pointers) {
pointers = pointers[:0]
}
pointers = append(pointers, mem.ZeroValue[T]())
return unsafe.Pointer(&pointers[len(pointers)-1]), nil
case ACTION_RESET:
clear(pointers)
pointers = pointers[:0]
case ACTION_SAVE:
if watermark == nil {
return nil, errors.New("pool: cannot save to nil watermark")
}
*watermark = uintptr(len(pointers))
case ACTION_RESTORE:
if watermark == nil {
return nil, errors.New("pool: cannot restore nil watermark")
}
clear(pointers[*watermark:])
pointers = pointers[:*watermark]
default:
panic("pool: unimplemented action - " + a.String())
}
return nil, nil
}
}
// Chunked is an Arena that groups allocations by size.
func Chunked(max_allocs_per_chunk uintptr) Arena {
type chunk struct {
data []byte
offset uintptr
saved uintptr
}
groups := make([][]chunk, 64)
return func(a Action, size, align uintptr, _ *uintptr) (unsafe.Pointer, error) {
switch a {
case ACTION_ALLOC:
aligned := mem.AlignForward(size, align)
if aligned == 0 {
aligned = 1
}
aligned = 1 << bits.Len(uint(aligned-1))
idx := bits.TrailingZeros(uint(aligned))
if idx >= len(groups) {
groups = append(groups, make([][]chunk, idx-len(groups)+1)...)
}
group := groups[idx]
if len(group) == 0 {
group = append(group, chunk{
data: make([]byte, aligned*max_allocs_per_chunk),
})
}
c := &group[len(group)-1]
if c.offset+aligned > uintptr(len(c.data)) {
group = append(group, chunk{
data: make([]byte, aligned*max_allocs_per_chunk),
})
c = &group[len(group)-1]
}
ptr := &c.data[c.offset]
c.offset += aligned
groups[idx] = group
return unsafe.Pointer(ptr), nil
case ACTION_RESET:
for _, g := range groups {
for i := range len(g) {
g[i].offset = 0
g[i].saved = 0
clear(g[i].data)
}
}
case ACTION_SAVE:
for _, g := range groups {
for i := range len(g) {
g[i].saved = g[i].offset
}
}
case ACTION_RESTORE:
for _, g := range groups {
for i := range len(g) {
g[i].offset = g[i].saved
}
}
default:
panic("chunked: unimplemented action - " + a.String())
}
return nil, nil
}
}
// Nil is an Arena that always returns an error.
//
// Note: This is useful for tracking usage locations
func Nil() Arena {
return func(a Action, size, align uintptr, watermark *uintptr) (unsafe.Pointer, error) {
return nil, errors.New("use of nil allocator")
}
}
// Region wraps an Arena, restoring it to its previous state when Reset is called.
func Region(arena Arena) Arena {
watermark := Save(arena)
return func(a Action, size, align uintptr, wm *uintptr) (unsafe.Pointer, error) {
if a == ACTION_RESET {
Restore(arena, watermark)
return nil, nil
}
return arena(a, size, align, wm)
}
}
// Split wraps two [[Arena]]s, dispatching allocations to a particular one based on the requested size.
func Split(split_size uintptr, smaller, larger Arena) Arena {
var watermarks [2]uintptr
return func(a Action, size, align uintptr, watermark *uintptr) (unsafe.Pointer, error) {
switch a {
case ACTION_ALLOC:
if size <= split_size {
return smaller(a, size, align, watermark)
}
return larger(a, size, align, watermark)
case ACTION_RESET:
Reset(smaller)
Reset(larger)
case ACTION_SAVE:
watermarks[0] = Save(smaller)
watermarks[1] = Save(larger)
case ACTION_RESTORE:
Restore(smaller, watermarks[0])
Restore(larger, watermarks[1])
default:
panic("split: unimplemented action - " + a.String())
}
return nil, nil
}
}
// Logger wraps an Arena, logging its usage locations.
func Logger(arena Arena) Arena {
return func(a Action, size, align uintptr, watermark *uintptr) (unsafe.Pointer, error) {
// We expect allocators to be used via the high-level API, so we grab the caller location relative to that.
// @todo(judah): can we determine this dynamically?
_, file, line, ok := runtime.Caller(2)
if !ok {
file = "<unknown>"
line = 0
}
log.Printf("%s:%d - %s (size: %d, align: %d, watermark: %p)", file, line, a, size, align, watermark)
return arena(a, size, align, watermark)
}
}
// Concurrent wraps an Arena, ensuring it is safe for concurrent use.
func Concurrent(arena Arena) Arena {
mtx := new(sync.Mutex)
return func(a Action, size, align uintptr, watermark *uintptr) (unsafe.Pointer, error) {
mtx.Lock()
ptr, err := arena(a, size, align, watermark)
mtx.Unlock()
return ptr, err
}
}
// Pinned wraps an Arena, ensuring the memory returned is stable until Reset is called.
//
// The memory returned by Pinned is safe to pass over cgo boundaries.
func Pinned(arena Arena) Arena {
var pinner runtime.Pinner
return func(a Action, size, align uintptr, watermark *uintptr) (unsafe.Pointer, error) {
ptr, err := arena(a, size, align, watermark)
if err != nil {
return ptr, err
}
if a == ACTION_RESET {
pinner.Unpin()
} else {
pinner.Pin(ptr)
}
return ptr, err
}
}

279
arena/arenas_bench_test.go
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@ -1,279 +0,0 @@
package arena_test
import (
"errors"
"runtime"
"testing"
"unsafe"
"git.brut.systems/judah/xx/arena"
"git.brut.systems/judah/xx/mem"
)
func BenchmarkAlloc_New_Small(b *testing.B) {
var last *int
for i := range b.N {
v := new(int)
*v = i
last = v
if i%1000 == 0 {
last = nil
}
}
runtime.KeepAlive(last)
}
func BenchmarkAlloc_Closure_Small(b *testing.B) {
alloc := arena.Ring[int](16)
var last *int
for i := range b.N {
v := arena.New[int](alloc)
*v = i
last = v
if i%1000 == 0 {
arena.Reset(alloc)
}
}
runtime.KeepAlive(last)
}
func BenchmarkAlloc_Interface_Small(b *testing.B) {
alloc := NewLinear(16 * mem.Kilobyte)
var last *int
for i := range b.N {
v := New[int](alloc)
*v = i
last = v
if i%1000 == 0 {
Reset(alloc)
}
}
runtime.KeepAlive(last)
}
type large struct{ a, b, c, d, e, f, g, h, i int }
func BenchmarkAlloc_New_Large(b *testing.B) {
var last *large
for i := range b.N {
v := new(large)
v.e = i
last = v
if i%1000 == 0 {
last = nil
}
}
runtime.KeepAlive(last)
}
func BenchmarkAlloc_Closure_Large(b *testing.B) {
alloc := arena.Linear(128 * mem.Kilobyte)
var last *large
for i := range b.N {
v := arena.New[large](alloc)
v.e = i
last = v
if i%1000 == 0 {
arena.Reset(alloc)
}
}
runtime.KeepAlive(last)
}
func BenchmarkAlloc_Interface_Large(b *testing.B) {
alloc := NewLinear(128 * mem.Kilobyte)
var last *large
for i := range b.N {
v := New[large](alloc)
v.e = i
last = v
if i%1000 == 0 {
Reset(alloc)
}
}
runtime.KeepAlive(last)
}
func BenchmarkAlloc_Closure_HotPath(b *testing.B) {
alloc := arena.Linear(256)
var (
lastlarge *large
lastsmall *int
)
for i := range b.N {
if i%2 == 0 {
lastsmall = arena.New[int](alloc)
} else {
lastlarge = arena.New[large](alloc)
}
arena.Reset(alloc)
}
runtime.KeepAlive(lastlarge)
runtime.KeepAlive(lastsmall)
}
func BenchmarkAlloc_Interface_HotPath(b *testing.B) {
alloc := NewLinear(256)
var (
lastlarge *large
lastsmall *int
)
for i := range b.N {
if i%2 == 0 {
lastsmall = New[int](alloc)
} else {
lastlarge = New[large](alloc)
}
Reset(alloc)
}
runtime.KeepAlive(lastlarge)
runtime.KeepAlive(lastsmall)
}
func BenchmarkAlloc_Closure_Wrapped(b *testing.B) {
alloc := arena.Pinned(arena.Pinned(arena.Pinned(arena.Linear(256))))
var (
lastlarge *large
lastsmall *int
)
for i := range b.N {
if i%2 == 0 {
lastsmall = arena.New[int](alloc)
} else {
lastlarge = arena.New[large](alloc)
}
arena.Reset(alloc)
}
runtime.KeepAlive(lastlarge)
runtime.KeepAlive(lastsmall)
}
func BenchmarkAlloc_Interface_Wrapped(b *testing.B) {
alloc := NewPinned(NewPinned(NewPinned(NewLinear(256))))
var (
lastlarge *large
lastsmall *int
)
for i := range b.N {
if i%2 == 0 {
lastsmall = New[int](alloc)
} else {
lastlarge = New[large](alloc)
}
Reset(alloc)
}
runtime.KeepAlive(lastlarge)
runtime.KeepAlive(lastsmall)
}
type Allocator interface {
Proc(a arena.Action, size, align uintptr, watermark *uintptr) (unsafe.Pointer, error)
}
func New[T any](a Allocator) *T {
ptr, err := a.Proc(arena.ACTION_ALLOC, mem.Sizeof[T](), mem.Alignof[T](), nil)
if err != nil {
panic(err)
}
return (*T)(ptr)
}
func Reset(a Allocator) {
if _, err := a.Proc(arena.ACTION_RESET, 0, 0, nil); err != nil {
panic(err)
}
}
type Linear struct {
data []byte
maxsize uintptr
offset uintptr
}
func NewLinear(maxsize uintptr) *Linear {
return &Linear{
data: make([]byte, maxsize),
maxsize: maxsize,
}
}
func (l *Linear) Proc(a arena.Action, size, align uintptr, watermark *uintptr) (unsafe.Pointer, error) {
switch a {
case arena.ACTION_ALLOC:
aligned := mem.AlignForward(size, align)
if l.offset+aligned > l.maxsize {
return nil, errors.New("linear: out of memory")
}
ptr := &l.data[l.offset]
l.offset += aligned
return unsafe.Pointer(ptr), nil
case arena.ACTION_RESET:
clear(l.data)
l.offset = 0
case arena.ACTION_SAVE:
*watermark = l.offset
case arena.ACTION_RESTORE:
l.offset = *watermark
default:
panic("unimplemented action: " + a.String())
}
return nil, nil
}
type Pinned struct {
arena Allocator
pinner runtime.Pinner
}
func NewPinned(arena Allocator) *Pinned {
return &Pinned{arena: arena}
}
func (p *Pinned) Proc(a arena.Action, size, align uintptr, watermark *uintptr) (unsafe.Pointer, error) {
ptr, err := p.arena.Proc(a, size, align, watermark)
if err != nil {
return ptr, err
}
if a == arena.ACTION_RESET {
p.pinner.Unpin()
} else {
p.pinner.Pin(ptr)
}
return ptr, err
}

122
arena/arenas_test.go
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package arena_test
import (
"sync"
"testing"
"unsafe"
"git.brut.systems/judah/xx/arena"
"git.brut.systems/judah/xx/mem"
"git.brut.systems/judah/xx/testx"
)
func TestArenas_ThatShouldPanicWhenOOM(t *testing.T) {
arenas := []arena.Arena{
arena.Linear(1),
arena.Nil(),
}
for _, a := range arenas {
testx.ShouldPanic(t, func() {
_ = arena.New[int](a)
})
}
}
func TestArenas_ThatShouldClearAfterReset(t *testing.T) {
arenas := []arena.Arena{
arena.Linear(16),
arena.Chunked(16),
arena.Ring[uint16](2),
}
for _, a := range arenas {
x := arena.New[uint16](a)
y := arena.New[uint16](a)
*x, *y = 100, 200
arena.Reset(a)
testx.Expect(t, *x == 0, "x = %d, expected 0", *x)
testx.Expect(t, *y == 0, "y = %d, expected 0", *y)
}
}
func TestArenas_ThatShouldReuseMemoryAfterReset(t *testing.T) {
arenas := []arena.Arena{
arena.Linear(16),
arena.Chunked(16),
arena.Ring[uint16](2),
}
for _, a := range arenas {
x1 := arena.New[uint16](a)
y1 := arena.New[uint16](a)
arena.Reset(a)
x2 := arena.New[uint16](a)
y2 := arena.New[uint16](a)
testx.Expect(t, x1 == x2, "x1 = %p, x2 = %p", x1, x2)
testx.Expect(t, y1 == y2, "y1 = %p, y2 = %p", y1, y2)
}
}
func TestArenas_WithRegion(t *testing.T) {
arenas := []arena.Arena{
arena.Linear(256),
arena.Chunked(256),
arena.Ring[uint16](16),
}
var baseptrs []*uint16
for i, a := range arenas {
v := arena.New[uint16](a)
*v = uint16(i)
baseptrs = append(baseptrs, v)
}
for _, a := range arenas {
a := arena.Region(a)
for range 10 {
_ = arena.New[uint16](a)
}
arena.Reset(a)
}
for i, a := range arenas {
testx.Expect(t, *baseptrs[i] == uint16(i), "baseptrs[%d] = %d, expected %d", i, *baseptrs[i], i)
base := uintptr(unsafe.Pointer(baseptrs[i]))
next := uintptr(unsafe.Pointer(arena.New[uint16](a)))
testx.Expect(t, next-base == mem.Sizeof[uint16](), "delta was %d", next-base)
}
}
func TestConcurrent(t *testing.T) {
a := arena.Concurrent(arena.Linear(16))
base, err := a(arena.ACTION_ALLOC, 0, 1, nil)
testx.Expect(t, err == nil, "ACTION_ALLOC failed: %v", err)
var wg sync.WaitGroup
wg.Go(func() {
_ = arena.New[uint8](a)
_ = arena.New[uint8](a)
_ = arena.New[uint8](a)
_ = arena.New[uint8](a)
})
wg.Go(func() {
_ = arena.New[uint16](a)
_ = arena.New[uint16](a)
_ = arena.New[uint16](a)
_ = arena.New[uint16](a)
})
wg.Wait()
after, err := a(arena.ACTION_ALLOC, 0, 1, nil)
testx.Expect(t, err == nil, "ACTION_ALLOC failed: %v", err)
testx.Expect(t, uintptr(after)-uintptr(base) == 12, "diff is: %v", uintptr(after)-uintptr(base))
}

9
assert.go
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@ -1,9 +0,0 @@
//go:build !XX_DISABLE_ASSERT
package xx
func Assert(cond bool) {
if !cond {
panic("assertion failed")
}
}

7
assert_disabled.go
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@ -1,7 +0,0 @@
//go:build XX_DISABLE_ASSERT
package xx
func Assert(cond bool) {}
func Unreachable() {}

112
containerx/bucket/array.go
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@ -1,112 +0,0 @@
package bucket
import (
"iter"
)
const DefaultElementsPerBucket = 32
// Array is a resizable array whose values will never move in memory.
// This means it is safe to take a pointer to a value within the array
// while continuing to append to it.
type Array[T any] struct {
last int
elements_per_bucket int
buckets []bucket[T]
}
func (s *Array[T]) Init() {
s.InitWithCapacity(DefaultElementsPerBucket)
}
func (s *Array[T]) InitWithCapacity(elements_per_bucket int) {
if elements_per_bucket <= 0 {
elements_per_bucket = DefaultElementsPerBucket
}
s.elements_per_bucket = elements_per_bucket
s.buckets = s.buckets[:0]
s.buckets = append(s.buckets, make(bucket[T], 0, s.elements_per_bucket))
s.last = 0
}
func (s *Array[T]) Reset() {
s.buckets = s.buckets[:0]
s.last = 0
}
func (s *Array[T]) Append(value T) *T {
if len(s.buckets) == 0 {
s.Init()
}
if len(s.buckets[s.last]) == cap(s.buckets[s.last]) {
s.buckets = append(s.buckets, make(bucket[T], 0, s.elements_per_bucket))
s.last += 1
}
s.buckets[s.last] = append(s.buckets[s.last], value)
return &s.buckets[s.last][len(s.buckets[s.last])-1]
}
func (s *Array[T]) AppendMany(values ...T) (first *T) {
if len(values) == 0 {
return nil
}
first = s.Append(values[0])
if len(values) > 1 {
for _, v := range values[1:] {
s.Append(v)
}
}
return
}
func (s *Array[T]) Get(index int) *T {
b := s.buckets[index/s.elements_per_bucket]
return &b[index%s.elements_per_bucket]
}
func (s *Array[T]) Set(index int, value T) {
*s.Get(index) = value
}
func (s *Array[T]) Len() int {
return s.Cap() - (cap(s.buckets[s.last]) - len(s.buckets[s.last]))
}
func (s *Array[T]) Cap() int {
return len(s.buckets) * s.elements_per_bucket
}
func (s *Array[T]) Pointers() iter.Seq2[int, *T] {
return func(yield func(int, *T) bool) {
for bi := range s.buckets {
startIdx := bi * s.elements_per_bucket
for i := range s.buckets[bi] {
if !yield(startIdx+i, &s.buckets[bi][i]) {
return
}
}
}
}
}
func (s *Array[T]) Values() iter.Seq2[int, T] {
return func(yield func(int, T) bool) {
for bi, b := range s.buckets {
startIdx := bi * s.elements_per_bucket
for i := range b {
if !yield(startIdx+i, b[i]) {
return
}
}
}
}
}
type bucket[T any] = []T

70
containerx/bucket/array_test.go
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@ -1,70 +0,0 @@
package bucket_test
import (
"runtime"
"testing"
"git.brut.systems/judah/xx/containerx/bucket"
"git.brut.systems/judah/xx/testx"
)
func TestArray_StableWithGC(t *testing.T) {
type valuewithptr struct {
value int
ptr *int
}
var arr bucket.Array[valuewithptr]
aptr := arr.Append(valuewithptr{value: 10, ptr: nil})
bptr := arr.Append(valuewithptr{value: 20, ptr: &aptr.value})
const N = 1000
for i := range N {
arr.Append(valuewithptr{value: i})
runtime.GC()
}
testx.Expect(t, arr.Get(0) == aptr)
testx.Expect(t, arr.Get(1) == bptr)
testx.Expect(t, arr.Len() == N+2, "len was %d", arr.Len())
testx.Expect(t, bptr.ptr != nil && bptr.value == 20)
testx.Expect(t, bptr.ptr == &aptr.value, "%p vs. %p", bptr.ptr, &aptr.value)
}
func BenchmarkArray_RandomAccess(b *testing.B) {
var arr bucket.Array[int]
for i := range b.N {
arr.Append(i * i)
}
b.ResetTimer()
for i := range b.N {
arr.Get(i % b.N)
}
}
func BenchmarkArray_Append(b *testing.B) {
var arr bucket.Array[int]
for i := range b.N {
arr.Append(i * i)
}
arr.Reset()
for i := range b.N {
arr.Append(i * i)
}
}
func BenchmarkArray_Iteration(b *testing.B) {
var arr bucket.Array[int]
for i := range b.N {
arr.Append(i * i)
}
b.ResetTimer()
sum := 0
for _, v := range arr.Values() {
sum += v
}
}

174
containerx/xar/xar.go
View file

@ -1,174 +0,0 @@
package xar
import (
"iter"
"math/bits"
"unsafe"
"git.brut.systems/judah/xx"
)
const (
DefaultChunkSizeShift = 4
)
// Xar is an implementation of Andrew Reece's Xar (Exponential Array).
//
// See: https://www.youtube.com/watch?v=i-h95QIGchY
type Xar[T any] struct {
shift uint8
count uint64
chunks [][]T
}
func (x *Xar[T]) Init() {
x.InitWithSize(DefaultChunkSizeShift)
}
func (x *Xar[T]) InitWithSize(size_shift uint8) {
if len(x.chunks) != 0 {
x.Reset()
}
x.shift = size_shift
}
func (x *Xar[T]) Reset() {
for _, c := range x.chunks {
clear(c)
}
x.count = 0
}
func (x *Xar[T]) Append(value T) *T {
if x.shift == 0 {
x.Init()
}
chunk_idx, idx_in_chunk, chunk_cap := x.getChunk(x.count)
x.count += 1
if chunk_idx >= uint64(len(x.chunks)) {
x.chunks = append(x.chunks, make([]T, chunk_cap))
}
slot := &x.chunks[chunk_idx][idx_in_chunk]
*slot = value
return slot
}
func (x *Xar[T]) AppendMany(values ...T) *T {
if len(values) == 0 {
return nil
}
first := x.Append(values[0])
if len(values) > 1 {
for _, v := range values[1:] {
x.Append(v)
}
}
return first
}
func (x *Xar[T]) Get(index int) *T {
chunk_idx, idx_in_chunk, _ := x.getChunk(uint64(index))
return &x.chunks[chunk_idx][idx_in_chunk]
}
func (x *Xar[T]) Set(index int, value T) {
*x.Get(index) = value
}
func (x *Xar[T]) Remove(index int) {
x.Set(index, *x.Get(int(x.count - 1)))
x.count -= 1
}
func (x *Xar[T]) Len() int {
return int(x.count)
}
func (x *Xar[T]) Cap() (l int) {
for _, c := range x.chunks {
l += cap(c)
}
return
}
func (x *Xar[T]) Pointers() iter.Seq2[int, *T] {
return func(yield func(int, *T) bool) {
idx := -1
for chunk_idx, idx_in_chunk := range x.iter() {
idx += 1
if !yield(idx, &x.chunks[chunk_idx][idx_in_chunk]) {
break
}
}
}
}
func (x *Xar[T]) Values() iter.Seq2[int, T] {
return func(yield func(int, T) bool) {
idx := -1
for chunk_idx, idx_in_chunk := range x.iter() {
idx += 1
if !yield(idx, x.chunks[chunk_idx][idx_in_chunk]) {
break
}
}
}
}
func (x *Xar[T]) iter() iter.Seq2[uint64, uint64] {
return func(yield func(uint64, uint64) bool) {
chunk_size := 1 << x.shift
outer:
for chunk_idx := range x.chunks {
for idx_in_chunk := range chunk_size - 1 {
if uint64(chunk_idx+idx_in_chunk) >= uint64(x.count) {
break outer
}
if !yield(uint64(chunk_idx), uint64(idx_in_chunk)) {
break outer
}
}
chunk_size <<= xx.BoolUint(chunk_idx > 0)
}
}
}
func (x *Xar[T]) getChunk(index uint64) (chunk_idx uint64, idx_in_chunk uint64, chunk_cap uint64) {
if true /* branchless */ {
var (
i_shift = index >> x.shift
i_shift2 = i_shift != 0
msb = msb64(i_shift | 1)
b = uint64(*(*uint8)(unsafe.Pointer(&i_shift2)))
)
chunk_idx = msb + b
idx_in_chunk = index - (b << (msb + uint64(x.shift)))
chunk_cap = 1 << (msb + uint64(x.shift))
} else {
idx_in_chunk = index
chunk_cap = 1 << x.shift
i_shift := index >> x.shift
if i_shift > 0 {
chunk_idx = msb64(i_shift | 1)
chunk_cap = 1 << (chunk_idx + uint64(x.shift))
idx_in_chunk -= chunk_cap
chunk_idx += 1
}
}
return
}
func msb64(x uint64) uint64 {
return uint64(63 - bits.LeadingZeros64(x))
}

105
containerx/xar/xar_test.go
View file

@ -1,105 +0,0 @@
package xar_test
import (
"runtime"
"testing"
"git.brut.systems/judah/xx/containerx/xar"
"git.brut.systems/judah/xx/testx"
)
func TestXar_StableWithGC(t *testing.T) {
type valuewithptr struct {
value int
ptr *int
}
var x xar.Xar[valuewithptr]
x.InitWithSize(8)
aptr := x.Append(valuewithptr{value: 10, ptr: nil})
bptr := x.Append(valuewithptr{value: 20, ptr: &aptr.value})
const N = 1000
for i := range N {
x.Append(valuewithptr{value: i})
runtime.GC()
}
testx.Expect(t, x.Get(0) == bptr)
testx.Expect(t, x.Get(1) == bptr)
testx.Expect(t, x.Len() == N+2, "len was %d", x.Len())
testx.Expect(t, bptr.ptr != nil && bptr.value == 20)
testx.Expect(t, bptr.ptr == &aptr.value, "%p vs. %p", bptr.ptr, &aptr.value)
}
func TestXar_ResetAndReuse(t *testing.T) {
var x xar.Xar[int]
start := x.Append(60)
x.AppendMany(10, 20, 30, 40, 50)
x.Reset()
runtime.GC()
testx.Expect(t, x.Cap() != 0)
testx.Expect(t, x.Len() == 0)
x.Append(0xFF)
x.Append(0xFC)
x.Append(0xFB)
testx.Expect(t, x.Get(0) == start)
testx.Expect(t, x.Len() == 3)
}
func TestXar_Iterators(t *testing.T) {
var x xar.Xar[int]
x.AppendMany(0, 1, 2, 3, 4, 5)
iterations := 0
for i, v := range x.Values() {
iterations += 1
testx.Expect(t, v == i, "v: %d, i: %d", v, i)
}
testx.Expect(t, iterations == x.Len())
}
func BenchmarkXar_Append(b *testing.B) {
var x xar.Xar[int]
for i := range b.N {
x.Append(i * i)
}
x.Reset()
for i := range b.N {
x.Append(i * i)
}
}
func BenchmarkXar_RandomAccess(b *testing.B) {
var x xar.Xar[int]
for i := range b.N {
x.Append(i * i)
}
b.ResetTimer()
for i := range b.N {
x.Get(i % b.N)
}
}
func BenchmarkXar_Iteration(b *testing.B) {
var x xar.Xar[int]
for i := range b.N {
x.Append(i * i)
}
b.ResetTimer()
sum := 0
for _, v := range x.Values() {
sum += v
}
}

2
go.mod
View file

@ -1,5 +1,3 @@
module git.brut.systems/judah/xx module git.brut.systems/judah/xx
go 1.25.0 go 1.25.0
require github.com/ebitengine/purego v0.9.1

2
go.sum
View file

@ -1,2 +0,0 @@
github.com/ebitengine/purego v0.9.1 h1:a/k2f2HQU3Pi399RPW1MOaZyhKJL9w/xFpKAg4q1s0A=
github.com/ebitengine/purego v0.9.1/go.mod h1:iIjxzd6CiRiOG0UyXP+V1+jWqUXVjPKLAI0mRfJZTmQ=

112
mem/mem.go
View file

@ -1,112 +0,0 @@
package mem
import (
"unsafe"
)
const (
Kilobyte uintptr = 1 << (10 * (iota + 1))
Megabyte
Gigabyte
Terabyte
)
// Sizeof returns the size (in bytes) of the given type.
//
// Not to be confused with [unsafe.Sizeof] which returns the size of a type via an expression.
func Sizeof[T any]() uintptr {
return unsafe.Sizeof(*(*T)(nil))
}
// Alignof returns the alignment (in bytes) of the given type.
//
// Not to be confused with [unsafe.AlignOf] which returns the alignment of a type via an expression.
func Alignof[T any]() uintptr {
return unsafe.Alignof(*(*T)(nil))
}
// ZeroValue returns the zero value of a given type.
func ZeroValue[T any]() (_ T) {
return
}
// BitCast performs a bit conversion between two types of the same size.
//
// BitCast panics if the sizes of the types differ.
func BitCast[TOut any, TIn any](value *TIn) TOut {
if Sizeof[TOut]() != Sizeof[TIn]() {
panic("bitcast: sizes of types must match")
}
return *((*TOut)(unsafe.Pointer(value)))
}
// BitCastValue performs a bit conversion between two types of the same size.
//
// BitCastValue panics if the sizes of the types differ.
func BitCastValue[TOut any, TIn any](value TIn) TOut {
if Sizeof[TOut]() != Sizeof[TIn]() {
panic("bitcast: sizes of types must match")
}
return *((*TOut)(unsafe.Pointer(&value)))
}
// UnsafeCast performs a bit conversion between two types without checking if their sizes match.
func UnsafeCast[TOut any, TIn any](value *TIn) TOut {
return *((*TOut)(unsafe.Pointer(value)))
}
// UnsafeCastValue performs a bit conversion between two types without checking if their sizes match.
func UnsafeCastValue[TOut any, TIn any](value TIn) TOut {
return *((*TOut)(unsafe.Pointer(&value)))
}
// Copy copies size number of bytes from src into dst.
//
// Returns dst.
func Copy(dst, src unsafe.Pointer, size uintptr) unsafe.Pointer {
copy(unsafe.Slice((*byte)(dst), size), unsafe.Slice((*byte)(src), size))
return dst
}
// Clear overwrites 'count' number of bytes in 'dst' with a particular value.
//
// Returns dst.
func Clear(dst unsafe.Pointer, value byte, count uintptr) unsafe.Pointer {
b := (*byte)(dst)
for range count { // @todo: loop unroll/maybe use asm?
*b = value
b = (*byte)(unsafe.Add(dst, 1))
}
return dst
}
// Zero overwrites 'count' number of bytes in 'dst' with zeros.
//
// Returns dst.
func Zero(dst unsafe.Pointer, count uintptr) unsafe.Pointer {
return Clear(dst, 0, count)
}
// AlignForward returns an address align to the next power-of-two alignment.
func AlignForward(address uintptr, alignment uintptr) uintptr {
if alignment == 0 || (alignment&(alignment-1)) != 0 {
panic("alignforward: alignment must be a power of two")
}
return (address + alignment - 1) &^ (alignment - 1)
}
// AlignBackward returns an address align to the previous power-of-two alignment.
func AlignBackward(address uintptr, alignment uintptr) uintptr {
if alignment == 0 || (alignment&(alignment-1)) != 0 {
panic("alignbackward: alignment must be a power of two")
}
return address &^ (alignment - 1)
}
// Aligned returns if the address is aligned to the given power-of-two alignment.
func Aligned(address uintptr, alignment uintptr) bool {
if alignment == 0 || (alignment&(alignment-1)) != 0 {
panic("aligned: alignment must be a power of two")
}
return address&(alignment-1) == 0
}

26
mem/mem_test.go
View file

@ -1,26 +0,0 @@
package mem_test
import (
"testing"
"git.brut.systems/judah/xx/mem"
)
func TestBitCast(t *testing.T) {
a := uint32(0xFFFF_FFFF)
b := mem.BitCast[float32](&a)
c := mem.BitCast[uint32](&b)
if a != c {
t.Fail()
}
v := uint8(0xFF)
d := mem.BitCast[int8](&v)
if d != -1 {
t.Fail()
}
e := mem.BitCast[uint8](&d)
if e != 255 {
t.Fail()
}
}

78
osthread/osthread.go
View file

@ -1,78 +0,0 @@
// Package osthread allows functions to be called on the main operating system thread.
//
// Usage:
//
// func main() {
// osthread.Start(Entrypoint) // Initialize osthread and calls Entrypoint. Blocks until Entrypoint returns.
// }
//
// func Entrypoint() {
// osthread.Call(FuncA) // Call FuncA on the main operating system thread, block until it returns
// // ...
// osthread.Go(FuncB) // Schedule FuncB to be called on the main operating system thread
// // ...
// }
package osthread
import (
"runtime"
)
// Start allows arbitrary functions to be run on the main operating system thread.
//
// Start must be called from the program's main function. Once called, it blocks until entrypoint returns.
func Start(entrypoint func()) {
defer runtime.UnlockOSThread()
done := make(chan any)
// Immediately queue entrypoint
go func() {
defer func() {
done <- nil
}()
entrypoint()
}()
// Call functions in our queue until entrypoint returns.
// These functions are called on the main operating system thread.
for {
select {
case fn := <-queue:
fn()
case <-done:
return
}
}
}
// Go schedules a function to be run on the main operating system thread, returning immediately.
func Go(fn func()) {
queue <- fn
}
// Call schedules a function to be run on the main operating system thread, blocking until it returns.
func Call(fn func()) {
if onmainthread() {
fn()
} else {
done := make(chan any)
queue <- func() {
defer func() {
done <- nil
}()
fn()
}
<-done
}
}
var queue chan func()
func init() {
runtime.LockOSThread()
queue = make(chan func(), runtime.GOMAXPROCS(0))
}

7
osthread/osthread_anyone.go
View file

@ -1,7 +0,0 @@
//go:build !(windows || linux || darwin)
package osthread
func onmainthread() bool {
return false
}

33
osthread/osthread_darwin.go
View file

@ -1,33 +0,0 @@
//go:build darwin
package osthread
import "github.com/ebitengine/purego/objc"
func onmainthread() bool {
return objc.Send[bool](objc.ID(cls_nsthread), sel_isMainThread)
}
var (
cls_nsthread objc.Class
cls_nsapplication objc.Class
cls_nsapp objc.Class
sel_isMainThread objc.SEL
sel_sharedApplication objc.SEL
sel_run objc.SEL
)
func init() {
cls_nsthread = objc.GetClass("NSThread")
cls_nsapplication = objc.GetClass("NSApplication")
cls_nsapp = objc.GetClass("NSApp")
sel_isMainThread = objc.RegisterName("isMainThread")
sel_sharedApplication = objc.RegisterName("sharedApplication")
sel_run = objc.RegisterName("run")
// Just a bit of magic
objc.ID(cls_nsapplication).Send(sel_sharedApplication)
objc.ID(cls_nsapp).Send(sel_run)
}

26
osthread/osthread_linux.go
View file

@ -1,26 +0,0 @@
//go:build linux
package osthread
import (
"github.com/ebitengine/purego"
)
func onmainthread() bool {
return getpid() == gettid()
}
var (
getpid func() int32
gettid func() int32
)
func init() {
libc, err := purego.Dlopen("libc.so.6", purego.RTLD_GLOBAL|purego.RTLD_NOW)
if err != nil {
panic(err)
}
purego.RegisterLibFunc(&getpid, libc, "getpid")
purego.RegisterLibFunc(&gettid, libc, "gettid")
}

25
osthread/osthread_windows.go
View file

@ -1,25 +0,0 @@
//go:build windows
package osthread
import (
"syscall"
"github.com/ebitengine/purego"
)
func onmainthread() bool {
return mainThreadId == getCurrentThreadId()
}
var (
mainThreadId int32
getCurrentThreadId func() int32
)
func init() {
kernel32 := syscall.NewLazyDLL("kernel32.dll").Handle()
purego.RegisterLibFunc(&getCurrentThreadId, kernel32, "GetCurrentThreadId")
mainThreadId = getCurrentThreadId() // init is always called on the main thread
}

87
pointer/pinned.go
View file

@ -1,87 +0,0 @@
package pointer
import (
"runtime"
"unsafe"
"git.brut.systems/judah/xx/mem"
)
type Pinned[T any] struct {
base unsafe.Pointer
pinner runtime.Pinner
}
func Pin[T any](ptr *T) (r Pinned[T]) {
r.pinner.Pin(ptr)
r.base = unsafe.Pointer(ptr)
return
}
func Cast[TOut, TIn any](p Pinned[TIn]) Pinned[TOut] {
return Pinned[TOut]{
base: unsafe.Pointer(p.base),
pinner: p.pinner,
}
}
func (p Pinned[T]) Unpin() {
p.pinner.Unpin()
p.base = nil
}
func (p Pinned[T]) Pointer() unsafe.Pointer {
return p.base
}
func (p Pinned[T]) Address() uintptr {
return uintptr(p.base)
}
func (p Pinned[T]) Nil() bool {
return p.base == nil
}
func (p Pinned[T]) Add(amount uintptr) Pinned[T] {
return Pinned[T]{
base: unsafe.Pointer(uintptr(p.base) + amount),
pinner: p.pinner,
}
}
func (p Pinned[T]) Sub(amount uintptr) Pinned[T] {
return Pinned[T]{
base: unsafe.Pointer(uintptr(p.base) - amount),
pinner: p.pinner,
}
}
func (p Pinned[T]) Aligned() bool {
return mem.Aligned(uintptr(p.base), mem.Alignof[T]())
}
func (p Pinned[T]) AlignForward() Pinned[T] {
return Pinned[T]{
base: unsafe.Pointer(mem.AlignForward(uintptr(p.base), mem.Alignof[T]())),
pinner: p.pinner,
}
}
func (p Pinned[T]) AlignBackward() Pinned[T] {
return Pinned[T]{
base: unsafe.Pointer(mem.AlignBackward(uintptr(p.base), mem.Alignof[T]())),
pinner: p.pinner,
}
}
func (p Pinned[T]) Load() T {
return *(*T)(p.base)
}
func (p Pinned[T]) Store(value T) {
*(*T)(p.base) = value
}
func (p Pinned[T]) Nth(index int) T {
return p.Add(uintptr(index) * mem.Sizeof[T]()).Load()
}

131
pointer/pinned_test.go
View file

@ -1,131 +0,0 @@
package pointer_test
import (
"testing"
"git.brut.systems/judah/xx/pointer"
)
func TestPointer_AlignForward(t *testing.T) {
tests := []struct {
name string
offset uintptr
}{
{"align 8 bytes", 1},
{"align 16 bytes", 3},
{"align 32 bytes", 7},
{"align 64 bytes", 15},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
value := int32(789)
pinned := pointer.Pin(&value)
defer pinned.Unpin()
// Add offset to misalign
misaligned := pinned.Add(tt.offset)
aligned := misaligned.AlignForward()
// Check alignment
if !aligned.Aligned() {
t.Errorf("Address %d is not aligned", aligned.Address())
}
// Check it's forward aligned (greater or equal)
if aligned.Address() < misaligned.Address() {
t.Errorf("Forward aligned address %d should be >= original %d", aligned.Address(), misaligned.Address())
}
})
}
}
func TestPointer_AlignBackward(t *testing.T) {
tests := []struct {
name string
offset uintptr
}{
{"align 8 bytes", 5},
{"align 16 bytes", 10},
{"align 32 bytes", 20},
{"align 64 bytes", 40},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
value := int32(321)
pinned := pointer.Pin(&value)
defer pinned.Unpin()
// Add offset to misalign
misaligned := pinned.Add(tt.offset)
aligned := misaligned.AlignBackward()
// Check alignment
if !aligned.Aligned() {
t.Errorf("Address %d is not aligned", aligned.Address())
}
// Check it's backward aligned (less or equal)
if aligned.Address() > misaligned.Address() {
t.Errorf("Backward aligned address %d should be <= original %d", aligned.Address(), misaligned.Address())
}
})
}
}
func TestPointer_Nth(t *testing.T) {
// Test with int32 array
arr := []int32{10, 20, 30, 40, 50}
pinned := pointer.Pin(&arr[0])
defer pinned.Unpin()
for i := 0; i < len(arr); i++ {
value := pinned.Nth(i)
if value != arr[i] {
t.Errorf("Index %d: expected %d, got %d", i, arr[i], value)
}
}
}
func TestPointer_NthFloat64(t *testing.T) {
// Test with a float64 array
arr := []float64{1.1, 2.2, 3.3, 4.4, 5.5}
pinned := pointer.Pin(&arr[0])
defer pinned.Unpin()
for i := 0; i < len(arr); i++ {
value := pinned.Nth(i)
if value != arr[i] {
t.Errorf("Index %d: expected %f, got %f", i, arr[i], value)
}
}
}
func TestPointerArithmeticChain(t *testing.T) {
value := int32(888)
pinned := pointer.Pin(&value)
defer pinned.Unpin()
// Test chaining operations
result := pinned.Add(16).Add(8).Sub(4)
expected := pinned.Address() + 16 + 8 - 4
if result.Address() != expected {
t.Errorf("Expected address %d, got %d", expected, result.Address())
}
}
func TestPointer_Cast(t *testing.T) {
value := int32(123)
i32 := pointer.Pin(&value)
defer i32.Unpin()
f32 := pointer.Cast[float32](i32)
f32.Store(3.14)
if value == 123 {
t.Errorf("Value should have been changed")
}
}

149
spmd/spmd.go
View file

@ -1,149 +0,0 @@
// Package spmd contains useful primitives for SPMD programs.
//
// Usage:
//
// func main() {
// // Create N execution lanes (<= 0 for GOMAXPROCS lanes),
// // and run 'Compute' across N lanes.
// spmd.Run(-1, Compute)
// }
//
// func Compute(lane spmd.Lane) {
// log.Printf("Lane %d/%d is executing", lane.Index, lane.Count)
//
// // Execute this code on a lane locked to the main thread (aka lane.Index == 0)
// // One lane will always be locked to the main thread
// if lane.Main() {
// data, err := os.ReadFile(...)
// if err != nil {
// panic(err)
// }
//
// // Send data to all lanes ("DATA" can be any value)
// lane.Store("DATA", string(data))
// }
//
// // Wait until all lanes are at this point
// lane.Sync()
//
// // Load stored data
// data := lane.Load("DATA").(string)
//
// // Get lane-specific access range for data
// lo, hi := lane.Range(len(data))
// for i := lo; i < hi; i++ {
// // ...
// }
// }
package spmd
import (
"runtime"
"sync"
"sync/atomic"
"git.brut.systems/judah/xx/osthread"
)
// Run will start executing the given function across N execution lanes,
// blocking until they have all finished executing.
//
// If nLanes is <= 0, GOMAXPROCS will be used.
//
// Run must be called from the program's main function.
func Run(nLanes int, fn func(lane Lane)) {
if nLanes <= 0 {
nLanes = runtime.GOMAXPROCS(0)
}
osthread.Start(func() {
s := new(state)
s.cond.L = &s.mtx
s.total = uint64(nLanes)
var wg sync.WaitGroup
for i := range s.total {
if i == 0 { // Lane 0 is always on the main thread
wg.Add(1)
osthread.Go(func() {
fn(Lane{state: s, Index: uint32(i), Count: uint32(s.total)})
wg.Done()
})
} else { // Everyone else gets scheduled like usual
wg.Go(func() {
fn(Lane{state: s, Index: uint32(i), Count: uint32(s.total)})
})
}
}
wg.Wait()
})
}
type state struct {
mtx sync.Mutex
cond sync.Cond
waiting atomic.Uint64
total uint64
userdata sync.Map
}
type Lane struct {
state *state
Index uint32
Count uint32
}
// Main returns if the lane is locked to the main thread.
func (l Lane) Main() bool {
return l.Index == 0
}
// Sync pauses the current lane until all lanes are at the same sync point.
func (l Lane) Sync() {
l.state.mtx.Lock()
defer l.state.mtx.Unlock()
if l.state.waiting.Add(1) >= l.state.total {
l.state.waiting.Store(0)
l.state.cond.Broadcast()
return
}
l.state.cond.Wait()
}
// Store sends 'value' to all lanes.
//
// Store can be called concurrently.
func (l Lane) Store(key, value any) {
l.state.userdata.Store(key, value)
}
// Load fetches a named value, returning nil if it does not exist.
//
// Load can be called concurrently.
func (l Lane) Load(key any) any {
v, ok := l.state.userdata.Load(key)
if !ok {
return nil
}
return v
}
// Range returns a lane's data range for the given length.
func (l Lane) Range(length int) (lo, hi uint) {
size := uint(length) / uint(l.state.total)
rem := uint(length) % uint(l.state.total)
if uint(l.Index) < rem {
lo = uint(l.Index) * (size + 1)
hi = lo + size + 1
} else {
lo = uint(l.Index)*size + rem
hi = lo + size
}
return
}

24
testx/testx.go
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@ -1,24 +0,0 @@
package testx
import "testing"
func Expect(t *testing.T, cond bool, message ...any) {
t.Helper()
if !cond {
if len(message) == 0 {
message = append(message, "expectation failed")
}
str := message[0].(string)
t.Fatalf(str, message[1:]...)
}
}
func ShouldPanic(t *testing.T, f func()) {
t.Helper()
defer func() { recover() }()
f()
t.Fatal("expected panic")
}

150
union/union.go
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@ -1,150 +0,0 @@
package union
import (
"errors"
"fmt"
"reflect"
"strings"
"unsafe"
"git.brut.systems/judah/xx/mem"
)
var (
ErrUninitializedAccess = errors.New("access of uninitialized union")
ErrInvalidType = errors.New("type does not exist within union")
)
// anystruct represents a struct type with any members.
//
// Note: because Go's type constraint system can't enforce
// this, anystruct is here for documentation purposes.
type anystruct any
// @note(judah): is there a way to declare the type parameters
// to allow 'type Value union.Of[...]' so users can define their
// own methods?
// Of represents a union of different types.
//
// Since members are accessed by type instead of name,
// T is expected to be a struct of types like so:
//
// type Value = union.Of[struct {
// int32
// uint32
// float32
// })
type Of[T anystruct] struct {
typ reflect.Type
mem []byte
}
func (u Of[T]) Size() uintptr {
return mem.Sizeof[T]()
}
// String returns the string representation of a union.
func (u Of[T]) String() string {
var b strings.Builder
fmt.Fprintf(&b, "union[%s] = ", reflect.TypeFor[T]().String())
if u.typ == nil {
b.WriteString("none")
} else {
b.WriteString(u.typ.String())
}
return b.String()
}
// Is returns true if the given type is currently stored in the union.
func Is[E any, T anystruct](u Of[T]) bool {
// Explicit invalid check to make sure invalid types don't result in false-positives.
if u.typ == nil {
return false
}
return u.typ == reflect.TypeFor[E]()
}
// Set overwrites the backing memory of a union with the given value; initializing the union if uninitialized.
//
// Set is unsafe and will not verify if the backing memory has enough capacity to store the value.
// Use [SetSafe] for more safety checks.
func Set[V any, T anystruct](u *Of[T], value V) {
if u.mem == nil {
u.mem = make([]byte, mem.Sizeof[T]())
}
unsafe.Slice((*V)(unsafe.Pointer(&u.mem[0])), 1)[0] = value
u.typ = reflect.TypeFor[V]()
}
// SetSafe overwrites the backing memory of a union with the given value,
// returning an error if the value cannot be stored in the union.
//
// Use [Set] for fewer safety checks.
func SetSafe[V any, T anystruct](u *Of[T], value V) error {
if u.mem == nil {
u.mem = make([]byte, mem.Sizeof[T]())
}
vt := reflect.TypeFor[V]()
for _, field := range getInternalFields(*u) {
if field.Type == vt {
unsafe.Slice((*V)(unsafe.Pointer(&u.mem[0])), 1)[0] = value
u.typ = reflect.TypeFor[V]()
return nil
}
}
return fmt.Errorf("%s - %w", vt, ErrInvalidType)
}
// Get returns the union's backing memory interpreted as a value of type V, panicking if the union is uninitialized.
//
// Get is unsafe and will not verify if the type exists within the union.
// Use [GetSafe] for more safety checks.
func Get[V any, T anystruct](u Of[T]) V {
if u.mem == nil {
panic(ErrUninitializedAccess)
}
return unsafe.Slice((*V)(unsafe.Pointer(&u.mem[0])), 1)[0]
}
// GetSafe returns the union's backing memory interpreted as a value of type V, returning an error if the type
// does not exist within the union or the union is uninitialized.
//
// Use [Get] for fewer safety checks.
func GetSafe[V any, T anystruct](u Of[T]) (V, error) {
if u.mem == nil {
return mem.ZeroValue[V](), ErrUninitializedAccess
}
vt := reflect.TypeFor[V]()
for _, field := range getInternalFields(u) {
if field.Type == vt {
return unsafe.Slice((*V)(unsafe.Pointer(&u.mem[0])), 1)[0], nil
}
}
return mem.ZeroValue[V](), ErrInvalidType
}
// getInternalFields returns an array of reflect.StructField belonging
// to the internal type of a union.
func getInternalFields[U Of[T], T anystruct](_ U) []reflect.StructField {
backing := reflect.TypeFor[T]()
if backing.Kind() != reflect.Struct {
return nil
}
var fields []reflect.StructField
for i := range backing.NumField() {
fields = append(fields, backing.Field(i))
}
return fields
}

192
union/union_test.go
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@ -1,192 +0,0 @@
package union_test
import (
"testing"
"git.brut.systems/judah/xx/union"
)
func TestUnion_BasicGetSet(t *testing.T) {
type Numbers = union.Of[struct {
uint8
bool
}]
var num Numbers
union.Set[uint8](&num, 1)
b := union.Get[bool](num)
if !b {
t.Errorf("expected bool value to be true, was %v", b)
}
union.Set(&num, false)
i := union.Get[uint8](num)
if i != 0 {
t.Errorf("expected uint8 value to be 0, was %v", i)
}
}
type (
expr = union.Of[struct {
binaryExpr
intExpr
floatExpr
}]
binaryExpr struct {
Op string
Lhs expr
Rhs expr
}
intExpr int64
floatExpr float64
)
func TestUnion_OfStructs(t *testing.T) {
makeInt := func(value int64) (e expr) {
union.Set(&e, intExpr(value))
return
}
makeFloat := func(value float64) (e expr) {
union.Set(&e, floatExpr(value))
return
}
makeBinop := func(op string, lhs, rhs expr) (e expr) {
union.Set(&e, binaryExpr{
Op: op,
Lhs: lhs,
Rhs: rhs,
})
return
}
expr1 := makeBinop("+", makeInt(10), makeInt(20))
bin1 := union.Get[binaryExpr](expr1)
if bin1.Op != "+" {
t.Errorf("incorrect op returned from union: %s", bin1.Op)
}
if lhs := union.Get[intExpr](bin1.Lhs); lhs != 10 {
t.Errorf("incorrect lhs returned from union: %v", lhs)
}
if rhs := union.Get[intExpr](bin1.Rhs); rhs != 20 {
t.Errorf("incorrect rhs returned from union: %v", rhs)
}
expr2 := makeBinop("-", expr1, makeFloat(3.14))
bin2 := union.Get[binaryExpr](expr2)
if bin2.Op != "-" {
t.Errorf("incorrect op returned from union of union: %s", bin2.Op)
}
if lhs := union.Get[binaryExpr](bin2.Lhs); lhs.Op != "+" {
t.Errorf("incorrect lhs returned from union of union: %v", lhs)
}
if rhs := union.Get[floatExpr](bin2.Rhs); rhs != 3.14 {
t.Errorf("incorrect rhs returned from union of union: %v", rhs)
}
}
func TestUnion_OfPointers(t *testing.T) {
type Value = union.Of[struct {
*float64
*uint64
}]
var (
original uint64 = 100
value Value
)
if union.Is[*uint64](value) || union.Is[*float64](value) {
t.Error("union internal type was incorrect before usage")
}
union.Set(&value, &original)
if !union.Is[*uint64](value) {
t.Error("union internal type was incorrect after Set")
}
fptr := union.Get[*float64](value)
*fptr = 3.14
if original == 100 {
t.Error("original value did not change")
}
uptr := union.Get[*uint64](value)
*uptr = 200
if *fptr == 3.14 {
t.Error("float pointer value did not change after modification")
}
if original != 200 {
t.Errorf("original value was incorrect: %v", original)
}
}
func TestUnion_ToString(t *testing.T) {
type (
Struct = union.Of[struct {
int32
uint32
}]
Interface = union.Of[interface {
Int()
Bool()
}]
Bool = union.Of[bool]
)
var (
s Struct
i Interface
b Bool
)
if s.String() != "union[none] { int32; uint32 }" {
t.Errorf("valid union had invalid stringification: %s", s.String())
}
if i.String() != b.String() {
t.Errorf("invalid union had invalid stringification: %s, %s", i.String(), b.String())
}
union.Set[int32](&s, 10)
if s.String() != "union[int32] { int32; uint32 }" {
t.Errorf("valid union had invalid stringification after Set: %s", s.String())
}
}
func TestUnion_SafeUsage(t *testing.T) {
type Value = union.Of[struct {
int32
uint32
float32
}]
var v Value
if _, err := union.GetSafe[int32](v); err == nil {
t.Errorf("GetSafe did not error for an uninitialized union")
}
if err := union.SetSafe(&v, false); err == nil {
t.Error("SetSafe allowed invalid type")
}
if err := union.SetSafe[int32](&v, 10); err != nil {
t.Errorf("SetSafe failed with valid type: %s", err)
}
if _, err := union.GetSafe[bool](v); err == nil {
t.Errorf("GetSafe allowed invalid type")
}
if v, err := union.GetSafe[int32](v); err != nil {
t.Errorf("GetSafe failed with valid type: %s", err)
} else if v != 10 {
t.Errorf("GetSafe returned invalid value: %v", v)
}
}

49
utils.go Normal file
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@ -0,0 +1,49 @@
package xx
import (
"unsafe"
)
// New returns a newly allocated value with an initial value.
func New[T any](expr T) *T {
p := new(T)
*p = expr
return p
}
// Bitcast performs a bit conversion between two types of the same size.
//
// Bitcast panics if the sizes of the types differ.
func Bitcast[TOut any, TIn any](value TIn) TOut {
if SizeOf[TOut]() != SizeOf[TIn]() {
panic("bitcast: sizes of types must match")
}
return *((*TOut)(unsafe.Pointer(&value)))
}
// Copy copies src number of bytes into dst.
// Returns dst.
//
// Copy panics if src is smaller than dst.
func Copy[TDst any, TSrc any](dst *TDst, src *TSrc) *TDst {
if SizeOf[TSrc]() < SizeOf[TDst]() {
panic("copy: size of src must be >= dst")
}
MemCopy(unsafe.Pointer(dst), unsafe.Pointer(src), SizeOf[TDst]())
return dst
}
// MemCopy copies size number of bytes from src into dst.
// Returns dst.
func MemCopy(dst, src unsafe.Pointer, size uintptr) unsafe.Pointer {
copy(unsafe.Slice((*byte)(dst), size), unsafe.Slice((*byte)(src), size))
return dst
}
// SizeOf returns the size in bytes of the given type.
//
// Not to be confused with [unsafe.Sizeof] which returns the size of an expression.
func SizeOf[T any]() uintptr {
var zero T
return unsafe.Sizeof(zero)
}

62
utils_test.go Normal file
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@ -0,0 +1,62 @@
package xx_test
import (
"testing"
"unsafe"
"git.brut.systems/judah/xx"
)
func TestNew(t *testing.T) {
a := xx.New(uint32(1024))
if *a != 1024 {
t.Fail()
}
if unsafe.Sizeof(*a) != xx.SizeOf[uint32]() {
t.Fail()
}
b := xx.New(struct{ x, y, z float32 }{10, 20, 30})
if b.x != 10 {
t.Fail()
}
if b.y != 20 {
t.Fail()
}
if b.z != 30 {
t.Fail()
}
c := xx.New(b)
if c == &b {
t.Fail()
}
if (*c).x != 10 {
t.Fail()
}
if (*c).y != 20 {
t.Fail()
}
if (*c).z != 30 {
t.Fail()
}
}
func TestBitcast(t *testing.T) {
a := uint32(0xFFFF_FFFF)
b := xx.Bitcast[float32](a)
c := xx.Bitcast[uint32](b)
if a != c {
t.Fail()
}
d := xx.Bitcast[int8](uint8(0xFF))
if d != -1 {
t.Fail()
}
e := xx.Bitcast[uint8](d)
if e != 255 {
t.Fail()
}
}

60
xx.go
View file

@ -1,60 +0,0 @@
package xx
import (
"runtime"
"strings"
"unsafe"
"git.brut.systems/judah/xx/mem"
)
// Copy copies src number of bytes into dst.
// Returns dst.
//
// Copy panics if src is smaller than dst.
func Copy[TDst any, TSrc any](dst *TDst, src *TSrc) *TDst {
if mem.Sizeof[TSrc]() < mem.Sizeof[TDst]() {
panic("copy: size of src must be >= dst")
}
mem.Copy(unsafe.Pointer(dst), unsafe.Pointer(src), mem.Sizeof[TDst]())
return dst
}
// Clone returns a newly allocated shallow copy of the given value.
func Clone[T any](value *T) *T {
return Copy(new(T), value)
}
// BoolUint converts a boolean to an integer.
func BoolUint(b bool) uint {
return uint(*(*uint8)(unsafe.Pointer(&b)))
}
// CallerLocation returns the source location of the function CallerLocation is called in.
func CallerLocation() (file string, line int) {
_, file, line, _ = runtime.Caller(2)
// @todo: I'm sure there's a better way to do this
// Special-case when CallerLocation is called from main
if strings.Contains(file, "runtime") && strings.Contains(file, "proc.go") {
_, file, line, _ = runtime.Caller(1)
}
return
}
// HashLocation returns a hash of file and line, most likely returned from [CallerLocation].
func HashLocation(file string, line int) uint64 {
const (
FNV64_PRIME uint64 = 0x100000001B3
FNV64_BIAS uint64 = 0xCBF29CE484222325
)
h := FNV64_BIAS
for _, c := range file {
h = (h ^ uint64(c)) * FNV64_PRIME
}
h = (h ^ uint64(line)) * FNV64_PRIME
return h
}