Source file src/hash/crc32/gen_const_ppc64le.go
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25 package main
26
27 import (
28 "bytes"
29 "fmt"
30 "io/ioutil"
31 )
32
33 var blocking = 32 * 1024
34
35 func reflect_bits(b uint64, nr uint) uint64 {
36 var ref uint64
37
38 for bit := uint64(0); bit < uint64(nr); bit++ {
39 if (b & uint64(1)) == 1 {
40 ref |= (1 << (uint64(nr-1) - bit))
41 }
42 b = (b >> 1)
43 }
44 return ref
45 }
46
47 func get_remainder(poly uint64, deg uint, n uint) uint64 {
48
49 rem, _ := xnmodp(n, poly, deg)
50 return rem
51 }
52
53 func get_quotient(poly uint64, bits, n uint) uint64 {
54
55 _, div := xnmodp(n, poly, bits)
56 return div
57 }
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61
62
63 func xnmodp(n uint, poly uint64, deg uint) (uint64, uint64) {
64
65 var mod, mask, high, div uint64
66
67 if n < deg {
68 div = 0
69 return poly, div
70 }
71 mask = 1<<deg - 1
72 poly &= mask
73 mod = poly
74 div = 1
75 deg--
76 n--
77 for n > deg {
78 high = (mod >> deg) & 1
79 div = (div << 1) | high
80 mod <<= 1
81 if high != 0 {
82 mod ^= poly
83 }
84 n--
85 }
86 return mod & mask, div
87 }
88
89 func main() {
90 w := new(bytes.Buffer)
91
92 fmt.Fprintf(w, "// autogenerated: do not edit!\n")
93 fmt.Fprintf(w, "// generated from crc32/gen_const_ppc64le.go\n")
94 fmt.Fprintln(w)
95 fmt.Fprintf(w, "#include \"textflag.h\"\n")
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101 genCrc32ConstTable(w, 0xedb88320, "IEEE")
102 genCrc32ConstTable(w, 0x82f63b78, "Cast")
103 genCrc32ConstTable(w, 0xeb31d82e, "Koop")
104 b := w.Bytes()
105
106 err := ioutil.WriteFile("crc32_table_ppc64le.s", b, 0666)
107 if err != nil {
108 fmt.Printf("can't write output: %s\n", err)
109 }
110 }
111
112 func genCrc32ConstTable(w *bytes.Buffer, poly uint32, polyid string) {
113
114 ref_poly := reflect_bits(uint64(poly), 32)
115 fmt.Fprintf(w, "\n\t/* Reduce %d kbits to 1024 bits */\n", blocking*8)
116 j := 0
117 for i := (blocking * 8) - 1024; i > 0; i -= 1024 {
118 a := reflect_bits(get_remainder(ref_poly, 32, uint(i)), 32) << 1
119 b := reflect_bits(get_remainder(ref_poly, 32, uint(i+64)), 32) << 1
120
121 fmt.Fprintf(w, "\t/* x^%d mod p(x)%s, x^%d mod p(x)%s */\n", uint(i+64), "", uint(i), "")
122 fmt.Fprintf(w, "DATA ·%sConst+%d(SB)/8,$0x%016x\n", polyid, j*8, b)
123 fmt.Fprintf(w, "DATA ·%sConst+%d(SB)/8,$0x%016x\n", polyid, (j+1)*8, a)
124
125 j += 2
126 fmt.Fprintf(w, "\n")
127 }
128
129 for i := (1024 * 2) - 128; i >= 0; i -= 128 {
130 a := reflect_bits(get_remainder(ref_poly, 32, uint(i+32)), 32)
131 b := reflect_bits(get_remainder(ref_poly, 32, uint(i+64)), 32)
132 c := reflect_bits(get_remainder(ref_poly, 32, uint(i+96)), 32)
133 d := reflect_bits(get_remainder(ref_poly, 32, uint(i+128)), 32)
134
135 fmt.Fprintf(w, "\t/* x^%d mod p(x)%s, x^%d mod p(x)%s, x^%d mod p(x)%s, x^%d mod p(x)%s */\n", i+128, "", i+96, "", i+64, "", i+32, "")
136 fmt.Fprintf(w, "DATA ·%sConst+%d(SB)/8,$0x%08x%08x\n", polyid, j*8, c, d)
137 fmt.Fprintf(w, "DATA ·%sConst+%d(SB)/8,$0x%08x%08x\n", polyid, (j+1)*8, a, b)
138
139 j += 2
140 fmt.Fprintf(w, "\n")
141 }
142
143 fmt.Fprintf(w, "GLOBL ·%sConst(SB),RODATA,$4336\n", polyid)
144 fmt.Fprintf(w, "\n /* Barrett constant m - (4^32)/n */\n")
145 fmt.Fprintf(w, "DATA ·%sBarConst(SB)/8,$0x%016x\n", polyid, reflect_bits(get_quotient(ref_poly, 32, 64), 33))
146 fmt.Fprintf(w, "DATA ·%sBarConst+8(SB)/8,$0x0000000000000000\n", polyid)
147 fmt.Fprintf(w, "DATA ·%sBarConst+16(SB)/8,$0x%016x\n", polyid, reflect_bits((uint64(1)<<32)|ref_poly, 33))
148 fmt.Fprintf(w, "DATA ·%sBarConst+24(SB)/8,$0x0000000000000000\n", polyid)
149 fmt.Fprintf(w, "GLOBL ·%sBarConst(SB),RODATA,$32\n", polyid)
150 }
151
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