/
bv.go
195 lines (165 loc) · 3.48 KB
/
bv.go
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// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package gc
import "fmt"
const (
WORDSIZE = 4
WORDBITS = 32
WORDMASK = WORDBITS - 1
WORDSHIFT = 5
)
// A Bvec is a bit vector.
type Bvec struct {
n int32 // number of bits in vector
b []uint32 // words holding bits
}
func bvsize(n uint32) uint32 {
return ((n + WORDBITS - 1) / WORDBITS) * WORDSIZE
}
func bvbits(bv Bvec) int32 {
return bv.n
}
func bvwords(bv Bvec) int32 {
return (bv.n + WORDBITS - 1) / WORDBITS
}
func bvalloc(n int32) Bvec {
return Bvec{n, make([]uint32, bvsize(uint32(n))/4)}
}
type bulkBvec struct {
words []uint32
nbit int32
nword int32
}
func bvbulkalloc(nbit int32, count int32) bulkBvec {
nword := (nbit + WORDBITS - 1) / WORDBITS
return bulkBvec{
words: make([]uint32, nword*count),
nbit: nbit,
nword: nword,
}
}
func (b *bulkBvec) next() Bvec {
out := Bvec{b.nbit, b.words[:b.nword]}
b.words = b.words[b.nword:]
return out
}
// difference
func bvandnot(dst Bvec, src1 Bvec, src2 Bvec) {
for i, x := range src1.b {
dst.b[i] = x &^ src2.b[i]
}
}
func bvcmp(bv1 Bvec, bv2 Bvec) int {
if bv1.n != bv2.n {
Fatalf("bvequal: lengths %d and %d are not equal", bv1.n, bv2.n)
}
for i, x := range bv1.b {
if x != bv2.b[i] {
return 1
}
}
return 0
}
func bvcopy(dst Bvec, src Bvec) {
for i, x := range src.b {
dst.b[i] = x
}
}
func bvconcat(src1 Bvec, src2 Bvec) Bvec {
dst := bvalloc(src1.n + src2.n)
for i := int32(0); i < src1.n; i++ {
if bvget(src1, i) != 0 {
bvset(dst, i)
}
}
for i := int32(0); i < src2.n; i++ {
if bvget(src2, i) != 0 {
bvset(dst, i+src1.n)
}
}
return dst
}
func bvget(bv Bvec, i int32) int {
if i < 0 || i >= bv.n {
Fatalf("bvget: index %d is out of bounds with length %d\n", i, bv.n)
}
return int((bv.b[i>>WORDSHIFT] >> uint(i&WORDMASK)) & 1)
}
// bvnext returns the smallest index >= i for which bvget(bv, i) == 1.
// If there is no such index, bvnext returns -1.
func bvnext(bv Bvec, i int32) int {
if i >= bv.n {
return -1
}
// Jump i ahead to next word with bits.
if bv.b[i>>WORDSHIFT]>>uint(i&WORDMASK) == 0 {
i &^= WORDMASK
i += WORDBITS
for i < bv.n && bv.b[i>>WORDSHIFT] == 0 {
i += WORDBITS
}
}
if i >= bv.n {
return -1
}
// Find 1 bit.
w := bv.b[i>>WORDSHIFT] >> uint(i&WORDMASK)
for w&1 == 0 {
w >>= 1
i++
}
return int(i)
}
func bvisempty(bv Bvec) bool {
for i := int32(0); i < bv.n; i += WORDBITS {
if bv.b[i>>WORDSHIFT] != 0 {
return false
}
}
return true
}
func bvnot(bv Bvec) {
i := int32(0)
w := int32(0)
for ; i < bv.n; i, w = i+WORDBITS, w+1 {
bv.b[w] = ^bv.b[w]
}
}
// union
func bvor(dst Bvec, src1 Bvec, src2 Bvec) {
for i, x := range src1.b {
dst.b[i] = x | src2.b[i]
}
}
// intersection
func bvand(dst Bvec, src1 Bvec, src2 Bvec) {
for i, x := range src1.b {
dst.b[i] = x & src2.b[i]
}
}
func bvprint(bv Bvec) {
fmt.Printf("#*")
for i := int32(0); i < bv.n; i++ {
fmt.Printf("%d", bvget(bv, i))
}
}
func bvreset(bv Bvec, i int32) {
if i < 0 || i >= bv.n {
Fatalf("bvreset: index %d is out of bounds with length %d\n", i, bv.n)
}
mask := uint32(^(1 << uint(i%WORDBITS)))
bv.b[i/WORDBITS] &= mask
}
func bvresetall(bv Bvec) {
for i := range bv.b {
bv.b[i] = 0
}
}
func bvset(bv Bvec, i int32) {
if i < 0 || i >= bv.n {
Fatalf("bvset: index %d is out of bounds with length %d\n", i, bv.n)
}
mask := uint32(1 << uint(i%WORDBITS))
bv.b[i/WORDBITS] |= mask
}