github.com/Uhtred009/v2ray-core-1@v4.31.2+incompatible/common/crypto/internal/chacha_core_gen.go (about)

     1  // +build generate
     2  
     3  package main
     4  
     5  import (
     6  	"fmt"
     7  	"log"
     8  	"os"
     9  )
    10  
    11  func writeQuarterRound(file *os.File, a, b, c, d int) {
    12  	add := "x%d+=x%d\n"
    13  	xor := "x=x%d^x%d\n"
    14  	rotate := "x%d=(x << %d) | (x >> (32 - %d))\n"
    15  
    16  	fmt.Fprintf(file, add, a, b)
    17  	fmt.Fprintf(file, xor, d, a)
    18  	fmt.Fprintf(file, rotate, d, 16, 16)
    19  
    20  	fmt.Fprintf(file, add, c, d)
    21  	fmt.Fprintf(file, xor, b, c)
    22  	fmt.Fprintf(file, rotate, b, 12, 12)
    23  
    24  	fmt.Fprintf(file, add, a, b)
    25  	fmt.Fprintf(file, xor, d, a)
    26  	fmt.Fprintf(file, rotate, d, 8, 8)
    27  
    28  	fmt.Fprintf(file, add, c, d)
    29  	fmt.Fprintf(file, xor, b, c)
    30  	fmt.Fprintf(file, rotate, b, 7, 7)
    31  }
    32  
    33  func writeChacha20Block(file *os.File) {
    34  	fmt.Fprintln(file, `
    35  func ChaCha20Block(s *[16]uint32, out []byte, rounds int) {
    36    var x0,x1,x2,x3,x4,x5,x6,x7,x8,x9,x10,x11,x12,x13,x14,x15 = s[0],s[1],s[2],s[3],s[4],s[5],s[6],s[7],s[8],s[9],s[10],s[11],s[12],s[13],s[14],s[15]
    37  	for i := 0; i < rounds; i+=2 {
    38      var x uint32
    39      `)
    40  
    41  	writeQuarterRound(file, 0, 4, 8, 12)
    42  	writeQuarterRound(file, 1, 5, 9, 13)
    43  	writeQuarterRound(file, 2, 6, 10, 14)
    44  	writeQuarterRound(file, 3, 7, 11, 15)
    45  	writeQuarterRound(file, 0, 5, 10, 15)
    46  	writeQuarterRound(file, 1, 6, 11, 12)
    47  	writeQuarterRound(file, 2, 7, 8, 13)
    48  	writeQuarterRound(file, 3, 4, 9, 14)
    49  	fmt.Fprintln(file, "}")
    50  	for i := 0; i < 16; i++ {
    51  		fmt.Fprintf(file, "binary.LittleEndian.PutUint32(out[%d:%d], s[%d]+x%d)\n", i*4, i*4+4, i, i)
    52  	}
    53  	fmt.Fprintln(file, "}")
    54  	fmt.Fprintln(file)
    55  }
    56  
    57  func main() {
    58  	file, err := os.OpenFile("chacha_core.generated.go", os.O_WRONLY|os.O_TRUNC|os.O_CREATE, 0644)
    59  	if err != nil {
    60  		log.Fatalf("Failed to generate chacha_core.go: %v", err)
    61  	}
    62  	defer file.Close()
    63  
    64  	fmt.Fprintln(file, "package internal")
    65  	fmt.Fprintln(file)
    66  	fmt.Fprintln(file, "import \"encoding/binary\"")
    67  	fmt.Fprintln(file)
    68  	writeChacha20Block(file)
    69  }