github.com/megatontech/mynoteforgo@v0.0.0-20200507084910-5d0c6ea6e890/源码/syscall/js/typedarray.go (about)

     1  // Copyright 2018 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // +build js,wasm
     6  
     7  package js
     8  
     9  import (
    10  	"sync"
    11  	"unsafe"
    12  )
    13  
    14  var (
    15  	int8Array    = Global().Get("Int8Array")
    16  	int16Array   = Global().Get("Int16Array")
    17  	int32Array   = Global().Get("Int32Array")
    18  	uint8Array   = Global().Get("Uint8Array")
    19  	uint16Array  = Global().Get("Uint16Array")
    20  	uint32Array  = Global().Get("Uint32Array")
    21  	float32Array = Global().Get("Float32Array")
    22  	float64Array = Global().Get("Float64Array")
    23  )
    24  
    25  var _ Wrapper = TypedArray{} // TypedArray must implement Wrapper
    26  
    27  // TypedArray represents a JavaScript typed array.
    28  type TypedArray struct {
    29  	Value
    30  }
    31  
    32  // Release frees up resources allocated for the typed array.
    33  // The typed array and its buffer must not be accessed after calling Release.
    34  func (a TypedArray) Release() {
    35  	openTypedArraysMutex.Lock()
    36  	delete(openTypedArrays, a)
    37  	openTypedArraysMutex.Unlock()
    38  }
    39  
    40  var (
    41  	openTypedArraysMutex sync.Mutex
    42  	openTypedArrays      = make(map[TypedArray]interface{})
    43  )
    44  
    45  // TypedArrayOf returns a JavaScript typed array backed by the slice's underlying array.
    46  //
    47  // The supported types are []int8, []int16, []int32, []uint8, []uint16, []uint32, []float32 and []float64.
    48  // Passing an unsupported value causes a panic.
    49  //
    50  // TypedArray.Release must be called to free up resources when the typed array will not be used any more.
    51  func TypedArrayOf(slice interface{}) TypedArray {
    52  	a := TypedArray{typedArrayOf(slice)}
    53  	openTypedArraysMutex.Lock()
    54  	openTypedArrays[a] = slice
    55  	openTypedArraysMutex.Unlock()
    56  	return a
    57  }
    58  
    59  func typedArrayOf(slice interface{}) Value {
    60  	switch slice := slice.(type) {
    61  	case []int8:
    62  		if len(slice) == 0 {
    63  			return int8Array.New(memory.Get("buffer"), 0, 0)
    64  		}
    65  		return int8Array.New(memory.Get("buffer"), unsafe.Pointer(&slice[0]), len(slice))
    66  	case []int16:
    67  		if len(slice) == 0 {
    68  			return int16Array.New(memory.Get("buffer"), 0, 0)
    69  		}
    70  		return int16Array.New(memory.Get("buffer"), unsafe.Pointer(&slice[0]), len(slice))
    71  	case []int32:
    72  		if len(slice) == 0 {
    73  			return int32Array.New(memory.Get("buffer"), 0, 0)
    74  		}
    75  		return int32Array.New(memory.Get("buffer"), unsafe.Pointer(&slice[0]), len(slice))
    76  	case []uint8:
    77  		if len(slice) == 0 {
    78  			return uint8Array.New(memory.Get("buffer"), 0, 0)
    79  		}
    80  		return uint8Array.New(memory.Get("buffer"), unsafe.Pointer(&slice[0]), len(slice))
    81  	case []uint16:
    82  		if len(slice) == 0 {
    83  			return uint16Array.New(memory.Get("buffer"), 0, 0)
    84  		}
    85  		return uint16Array.New(memory.Get("buffer"), unsafe.Pointer(&slice[0]), len(slice))
    86  	case []uint32:
    87  		if len(slice) == 0 {
    88  			return uint32Array.New(memory.Get("buffer"), 0, 0)
    89  		}
    90  		return uint32Array.New(memory.Get("buffer"), unsafe.Pointer(&slice[0]), len(slice))
    91  	case []float32:
    92  		if len(slice) == 0 {
    93  			return float32Array.New(memory.Get("buffer"), 0, 0)
    94  		}
    95  		return float32Array.New(memory.Get("buffer"), unsafe.Pointer(&slice[0]), len(slice))
    96  	case []float64:
    97  		if len(slice) == 0 {
    98  			return float64Array.New(memory.Get("buffer"), 0, 0)
    99  		}
   100  		return float64Array.New(memory.Get("buffer"), unsafe.Pointer(&slice[0]), len(slice))
   101  	default:
   102  		panic("TypedArrayOf: not a supported slice")
   103  	}
   104  }