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buffer.go
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buffer.go
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//go:build darwin
// +build darwin
package metal
/*
#cgo LDFLAGS: -framework Cocoa -framework Metal
#include "Metal.h"
*/
import "C"
import (
"errors"
"math"
"unsafe"
)
var (
ErrInvalidBufferId = errors.New("Invalid buffer Id")
)
// A BufferId references a specific metal buffer created with NewBuffer*.
type BufferId int32
// Valid checks whether or not the buffer Id is valid and can be used to run a computational process
// on the GPU.
func (id BufferId) Valid() bool {
return id > 0
}
// A BufferType is a type that can be used to create a new metal buffer.
type BufferType interface {
~int8 | ~int16 | ~int32 | ~int64 | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~float32 | ~float64
}
// NewBuffer allocates a 1-dimensional block of memory that is accessible to both the CPU and GPU.
// It returns a unique Id for the buffer and a slice that wraps the new memory and has a length and
// capacity equal to width. The buffer is safe for reuse with any metal function.
//
// The Id is used to reference the buffer as an argument for the metal function.
//
// Only the contents of the slice should be modified. Its length and capacity and the pointer to its
// underlying array should not be altered.
//
// Use Fold to safely portion the slice into more dimensions. For example, to convert a
// one-dimensional slice into a two-dimensional slice, use Fold(buffer, width). Or to go from one
// dimensions to three, use Fold(Fold(buffer, width*height), width).
func NewBuffer[T BufferType](width int) (BufferId, []T, error) {
if width < 1 {
return 0, nil, errors.New("Invalid width")
}
numBytes := width * sizeof[T]()
if numBytes > math.MaxInt32 || numBytes < 0 {
return 0, nil, errors.New("Exceeded maximum number of bytes")
}
// Set up some space to hold a possible error message.
err := C.CString("")
defer C.free(unsafe.Pointer(err))
// Allocate memory for the new buffer.
bufferId := C.buffer_new(C.int(numBytes), &err)
if int(bufferId) == 0 {
return 0, nil, metalErrToError(err, "Unable to create buffer")
}
// Retrieve a pointer to the beginning of the new memory using the buffer's Id.
newBuffer := C.buffer_retrieve(bufferId, &err)
if newBuffer == nil {
return 0, nil, metalErrToError(err, "Unable to retrieve buffer")
}
// Wrap the buffer in a go slice.
slice := unsafe.Slice((*T)(newBuffer), width)
return BufferId(bufferId), slice, nil
}
// NewBufferWith is the same as NewBuffer, but it also initializes the buffer with the provided data.
func NewBufferWith[T BufferType](data []T) (BufferId, []T, error) {
bufferId, buffer, err := NewBuffer[T](len(data))
if err != nil {
return 0, nil, err
}
copy(buffer, data)
return bufferId, buffer, nil
}
// Close releases the buffer from the GPU memory. The buffer Id becomes invalid after this call.
func (id *BufferId) Close() error {
if id == nil || !id.Valid() {
return ErrInvalidBufferId
}
// Set up some space to hold a possible error message.
err := C.CString("")
defer C.free(unsafe.Pointer(err))
if !C.buffer_close(C.int(*id), &err) {
return metalErrToError(err, "Unable to free buffer")
}
// Clear the buffer Id to mark that it's no longer valid.
*id = 0
return nil
}