load_store.go

     1  // Copyright 2026 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  package flate
     6  
     7  // This file contains functions for loading and storing integers in little endian format.
     8  // These can be replaced with unsafe versions if deemed necessary.
     9  
    10  type indexer interface {
    11  	int | int8 | int16 | int32 | int64 | uint | uint8 | uint16 | uint32 | uint64
    12  }
    13  
    14  // loadLE8 will load from b at index i.
    15  func loadLE8[I indexer](b []byte, i I) byte {
    16  	return b[i]
    17  }
    18  
    19  // loadLE32 will load from b at index i.
    20  func loadLE32[I indexer](b []byte, i I) uint32 {
    21  	b = b[i : i+4]
    22  	return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
    23  }
    24  
    25  // loadLE64 will load from b at index i.
    26  func loadLE64[I indexer](b []byte, i I) uint64 {
    27  	b = b[i : i+8]
    28  	return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
    29  		uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
    30  }
    31  
    32  // storeLE64 will store v at start of b.
    33  func storeLE64(b []byte, v uint64) {
    34  	_ = b[7] // early bounds check to guarantee safety of writes below
    35  	b[0] = byte(v)
    36  	b[1] = byte(v >> 8)
    37  	b[2] = byte(v >> 16)
    38  	b[3] = byte(v >> 24)
    39  	b[4] = byte(v >> 32)
    40  	b[5] = byte(v >> 40)
    41  	b[6] = byte(v >> 48)
    42  	b[7] = byte(v >> 56)
    43  }
    44
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