1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
|
package main
import (
"bytes"
"flag"
"fmt"
"go/format"
"math/bits"
"os"
)
// pextByte handles single-byte PEXT operation
func pextByte(b, m uint8) uint8 {
var result, bitPos uint8
for i := uint8(0); i < 8; i++ {
if m&(1<<i) != 0 {
if b&(1<<i) != 0 {
result |= 1 << bitPos
}
bitPos++
}
}
return result
}
// pdepByte handles single-byte PDEP operation
func pdepByte(b, m uint8) uint8 {
var result, bitPos uint8
for i := uint8(0); i < 8; i++ {
if m&(1<<i) != 0 {
if b&(1<<bitPos) != 0 {
result |= 1 << i
}
bitPos++
}
}
return result
}
func generateTable(name string, data interface{}, comment string) string {
var buf bytes.Buffer
if comment != "" {
fmt.Fprintf(&buf, "// %s\n", comment)
}
fmt.Fprintf(&buf, "var %s = ", name)
switch v := data.(type) {
case [256]uint8:
buf.WriteString("[256]uint8{")
for i, val := range v {
if i%16 == 0 {
buf.WriteString("\n\t")
}
fmt.Fprintf(&buf, "%d,", val)
}
buf.WriteString("\n}")
case [256][256]uint8:
buf.WriteString("[256][256]uint8{")
for i, row := range v {
if i%4 == 0 {
buf.WriteString("\n\t")
}
buf.WriteString("{")
for j, val := range row {
if j%16 == 0 {
buf.WriteString("\n\t\t")
}
fmt.Fprintf(&buf, "%d,", val)
}
buf.WriteString("\n\t},")
}
buf.WriteString("\n}")
}
return buf.String()
}
func main() {
packageName := flag.String("pkg", "", "package name for generated code")
flag.Parse()
if *packageName == "" {
fmt.Fprintln(os.Stderr, "package name is required")
return
}
// Initialize lookup tables
var pextLUT [256][256]uint8
var pdepLUT [256][256]uint8
var popLUT [256]uint8
for b := 0; b < 256; b++ {
popLUT[b] = uint8(bits.OnesCount8(uint8(b)))
for m := 0; m < 256; m++ {
pextLUT[b][m] = pextByte(uint8(b), uint8(m))
pdepLUT[b][m] = pdepByte(uint8(b), uint8(m))
}
}
// Generate code
var buf bytes.Buffer
buf.WriteString("// Code generated by cmd/pextgen/main.go; DO NOT EDIT.\n")
buf.WriteString("//\n")
buf.WriteString("// To regenerate this file:\n")
buf.WriteString("// go run cmd/pextgen/main.go\n")
buf.WriteString("\n")
fmt.Fprintf(&buf, "package %s\n\n", *packageName)
tables := []struct {
name string
data interface{}
comment string
}{
{"pextLUT", pextLUT, "pextLUT contains pre-computed parallel bit extraction results"},
{"pdepLUT", pdepLUT, "pdepLUT contains pre-computed parallel bit deposit results"},
{"popLUT", popLUT, "popLUT contains pre-computed population counts"},
}
for _, table := range tables {
buf.WriteString(generateTable(table.name, table.data, table.comment))
buf.WriteString("\n\n")
}
// Format the generated code
formatted, err := format.Source(buf.Bytes())
if err != nil {
fmt.Fprintf(os.Stderr, "Failed to format code: %v\n", err)
os.Exit(1)
}
// Write to tables.go
err = os.WriteFile("pext.gen.go", formatted, 0644)
if err != nil {
fmt.Fprintf(os.Stderr, "Failed to write file: %v\n", err)
os.Exit(1)
}
}
|
