bitfield: update module
Alexey
GitHub
parent
8f06d60084
commit
bb587c27a8
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@ -25,56 +25,6 @@ const (
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SLOT_SIZE = 32
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)
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fn bitmask(bitnr int) u32 {
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return u32(u32(1) << u32(bitnr % SLOT_SIZE))
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}
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fn bitslot(size int) int {
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return size / SLOT_SIZE
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}
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fn bitget(instance BitField, bitnr int) int {
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return (instance.field[bitslot(bitnr)] >> (bitnr % SLOT_SIZE)) & u32(1)
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}
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fn bitset(instance mut BitField, bitnr int) {
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instance.field[bitslot(bitnr)] = instance.field[bitslot(bitnr)] | bitmask(bitnr)
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}
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fn bitclear(instance mut BitField, bitnr int) {
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instance.field[bitslot(bitnr)] = instance.field[bitslot(bitnr)] & ~bitmask(bitnr)
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}
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fn bittoggle(instance mut BitField, bitnr int) {
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instance.field[bitslot(bitnr)] = instance.field[bitslot(bitnr)] ^ bitmask(bitnr)
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}
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/*
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#define BITTEST(a, b) ((a)->field[BITSLOT(b)] & BITMASK(b))
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*/
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fn min(input1 int, input2 int) int {
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if input1 < input2 {
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return input1
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}
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else {
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return input2
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}
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}
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fn bitnslots(length int) int {
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return (length - 1) / SLOT_SIZE + 1
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}
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fn cleartail(instance mut BitField) {
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tail := instance.size % SLOT_SIZE
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if tail != 0 {
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// create a mask for the tail
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mask := u32((1 << tail) - 1)
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// clear the extra bits
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instance.field[bitnslots(instance.size) - 1] = instance.field[bitnslots(instance.size) - 1] & mask
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}
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}
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// public functions
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// from_bytes() converts a byte array into a bitfield.
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@ -86,10 +36,9 @@ pub fn from_bytes(input []byte) BitField {
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return output
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}
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// from_string() converts a string of characters ('0' and '1') to a bit
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// from_str converts a string of characters ('0' and '1') to a bit
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// array. Any character different from '0' is treated as '1'.
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pub fn from_string(input string) BitField {
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pub fn from_str(input string) BitField {
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mut output := new(input.len)
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for i in 0..input.len {
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if input[i] != `0` {
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@ -99,9 +48,8 @@ pub fn from_string(input string) BitField {
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return output
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}
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// str() converts the bit array to a string of characters ('0' and '1') and
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// str converts the bit array to a string of characters ('0' and '1') and
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// return the string
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pub fn (input BitField) str() string {
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mut output := ''
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for i in 0..input.size {
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@ -115,8 +63,7 @@ pub fn (input BitField) str() string {
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return output
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}
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//new() creates an empty bit array of capable of storing 'size' bits.
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// new creates an empty bit array of capable of storing 'size' bits.
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pub fn new(size int) BitField {
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output := BitField{
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size: size
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@ -132,121 +79,113 @@ pub fn del(instance *BitField) {
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}
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*/
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// getbit() returns the value (0 or 1) of bit number 'bit_nr' (count from
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// 0)
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// getbit returns the value (0 or 1) of bit number 'bit_nr' (count from 0).
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pub fn (instance BitField) getbit(bitnr int) int {
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if bitnr >= instance.size {return 0}
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return bitget(instance, bitnr)
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if bitnr >= instance.size {
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return 0
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}
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return (instance.field[bitslot(bitnr)] >> (bitnr % SLOT_SIZE)) & u32(1)
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}
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// setbit() set bit number 'bit_nr' to 1 (count from 0)
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// setbit sets bit number 'bit_nr' to 1 (count from 0).
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pub fn (instance mut BitField) setbit(bitnr int) {
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if bitnr >= instance.size {return}
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bitset(mut instance, bitnr)
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if bitnr >= instance.size {
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return
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}
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instance.field[bitslot(bitnr)] |= bitmask(bitnr)
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}
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// clearbit() clears (sets to zero) bit number 'bit_nr' (count from 0)
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// clearbit clears (sets to zero) bit number 'bit_nr' (count from 0).
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pub fn (instance mut BitField) clearbit(bitnr int) {
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if bitnr >= instance.size {return}
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bitclear(mut instance, bitnr)
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if bitnr >= instance.size {
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return
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}
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instance.field[bitslot(bitnr)] &= ~bitmask(bitnr)
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}
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// setall() sets all bits in the array to 1
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// setall sets all bits in the array to 1.
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pub fn (instance mut BitField) setall() {
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for i in 0..bitnslots(instance.size) {
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instance.field[i] = u32(-1)
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}
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cleartail(mut instance)
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instance.cleartail()
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}
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// clearall() clears (sets to zero) all bits in the array
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// clearall clears (sets to zero) all bits in the array.
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pub fn (instance mut BitField) clearall() {
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for i in 0..bitnslots(instance.size) {
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instance.field[i] = u32(0)
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}
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}
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// togglebit() change the value (from 0 to 1 or from 1 to 0) of bit
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// number 'bit_nr'
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// togglebit changes the value (from 0 to 1 or from 1 to 0) of bit
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// number 'bit_nr'.
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pub fn (instance mut BitField) togglebit(bitnr int) {
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if bitnr >= instance.size {return}
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bittoggle(mut instance, bitnr)
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if bitnr >= instance.size {
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return
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}
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instance.field[bitslot(bitnr)] ^= bitmask(bitnr)
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}
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// bfand() perform logical AND operation on every pair of bits from 'input1'
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// and 'input2' and return the result as a new array. If inputs differ in size,
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// bfand performs logical AND operation on every pair of bits from 'input1' and
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// 'input2' and returns the result as a new array. If inputs differ in size,
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// the tail of the longer one is ignored.
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pub fn bfand(input1 BitField, input2 BitField) BitField {
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size := min(input1.size, input2.size)
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bitnslots := bitnslots(size)
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mut output := new(size)
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mut i := 0
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for i < bitnslots {
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for i in 0..bitnslots {
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output.field[i] = input1.field[i] & input2.field[i]
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i++
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}
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cleartail(mut output)
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output.cleartail()
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return output
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}
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// bfnot() toggle all bits in a bit array and return the result as a new array
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// bfnot toggles all bits in a bit array and returns the result as a new array.
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pub fn bfnot(input BitField) BitField {
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size := input.size
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bitnslots := bitnslots(size)
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mut output := new(size)
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mut i := 0
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for i < bitnslots {
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for i in 0..bitnslots {
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output.field[i] = ~input.field[i]
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i++
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}
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cleartail(mut output)
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output.cleartail()
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return output
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}
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// bfor() perform logical OR operation on every pair of bits from 'input1' and
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// 'input2' and return the result as a new array. If inputs differ in size, the
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// tail of the longer one is ignored.
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// bfor performs logical OR operation on every pair of bits from 'input1' and
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// 'input2' and returns the result as a new array. If inputs differ in size,
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// the tail of the longer one is ignored.
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pub fn bfor(input1 BitField, input2 BitField) BitField {
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size := min(input1.size, input2.size)
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bitnslots := bitnslots(size)
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mut output := new(size)
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mut i := 0
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for i < bitnslots {
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for i in 0..bitnslots {
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output.field[i] = input1.field[i] | input2.field[i]
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i++
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}
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cleartail(mut output)
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output.cleartail()
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return output
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}
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// bfxor(input1 BitField, input2 BitField) perform logical XOR operation on
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// every pair of bits from 'input1' and 'input2' and return the result as a new
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// array. If inputs differ in size, the tail of the longer one is ignored.
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// bfxor perform logical XOR operation on every pair of bits from 'input1' and
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// 'input2' and returns the result as a new array. If inputs differ in size,
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// the tail of the longer one is ignored.
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pub fn bfxor(input1 BitField, input2 BitField) BitField {
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size := min(input1.size, input2.size)
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bitnslots := bitnslots(size)
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mut output := new(size)
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mut i := 0
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for i < bitnslots {
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for i in 0..bitnslots {
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output.field[i] = input1.field[i] ^ input2.field[i]
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i++
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}
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cleartail(mut output)
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output.cleartail()
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return output
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}
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// join() concatenates two bit arrays and return the result as a new array.
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// join concatenates two bit arrays and return the result as a new array.
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pub fn join(input1 BitField, input2 BitField) BitField {
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output_size := input1.size + input2.size
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mut output := new(output_size)
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@ -291,38 +230,33 @@ pub fn join(input1 BitField, input2 BitField) BitField {
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return output
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}
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// getsize() returns the number of bits the array can hold
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// getsize returns the number of bits the array can hold.
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pub fn (instance BitField) getsize() int {
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return instance.size
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}
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// clone() create a copy of a bit array
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pub fn clone(input BitField) BitField {
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bitnslots := bitnslots(input.size)
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mut output := new(input.size)
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mut i := 0
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for i < bitnslots {
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output.field[i] = input.field[i]
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// clone creates a copy of a bit array.
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pub fn (instance BitField) clone() BitField {
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bitnslots := bitnslots(instance.size)
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mut output := new(instance.size)
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for i in 0..bitnslots {
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output.field[i] = instance.field[i]
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i++
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}
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return output
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}
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// cmp() compare two bit arrays bit by bit and return 'true' if they are
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// cmp compares two bit arrays bit by bit and returns 'true' if they are
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// identical by length and contents and 'false' otherwise.
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pub fn cmp(input1 BitField, input2 BitField) bool {
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if input1.size != input2.size {return false}
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for i in 0..bitnslots(input1.size) {
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if input1.field[i] != input2.field[i] {return false}
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pub fn (instance BitField) cmp(input BitField) bool {
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if instance.size != input.size {return false}
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for i in 0..bitnslots(instance.size) {
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if instance.field[i] != input.field[i] {return false}
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}
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return true
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}
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// popcount() returns the number of set bits (ones) in the array
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// popcount returns the number of set bits (ones) in the array.
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pub fn (instance BitField) popcount() int {
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size := instance.size
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bitnslots := bitnslots(size)
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@ -343,16 +277,14 @@ pub fn (instance BitField) popcount() int {
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return count
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}
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// hamming () compute the Hamming distance between two bit arrays.
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// hamming computes the Hamming distance between two bit arrays.
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pub fn hamming (input1 BitField, input2 BitField) int {
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input_xored := bfxor(input1, input2)
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return input_xored.popcount()
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}
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// pos() checks if the array contains a sub-array 'needle' and returns its
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// pos checks if the array contains a sub-array 'needle' and returns its
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// position if it does, -1 if it does not, and -2 on error.
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pub fn (haystack BitField) pos(needle BitField) int {
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heystack_size := haystack.size
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needle_size := needle.size
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@ -364,7 +296,7 @@ pub fn (haystack BitField) pos(needle BitField) int {
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}
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for i := 0; i <= diff; i++ {
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needle_candidate := haystack.slice(i, needle_size + i)
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if cmp(needle_candidate, needle) {
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if needle_candidate.cmp(needle) {
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// needle matches a sub-array of haystack; return starting position of the sub-array
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return i
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}
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@ -373,9 +305,8 @@ pub fn (haystack BitField) pos(needle BitField) int {
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return -1
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}
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// slice() return a sub-array of bits between 'start_bit_nr' (included) and
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// 'end_bit_nr' (excluded)
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// slice returns a sub-array of bits between 'start_bit_nr' (included) and
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// 'end_bit_nr' (excluded).
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pub fn (input BitField) slice(_start int, _end int) BitField {
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// boundary checks
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mut start := _start
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@ -441,9 +372,8 @@ pub fn (input BitField) slice(_start int, _end int) BitField {
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return output
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}
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// reverse() reverses the order of bits in the array (swap the first with the
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// last, the second with the last but one and so on)
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// reverse reverses the order of bits in the array (swap the first with the
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// last, the second with the last but one and so on).
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pub fn (instance BitField) reverse() BitField {
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size := instance.size
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bitnslots := bitnslots(size)
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@ -451,20 +381,20 @@ pub fn (instance BitField) reverse() BitField {
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for i:= 0; i < (bitnslots - 1); i++ {
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for j in 0..SLOT_SIZE {
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if u32(instance.field[i] >> u32(j)) & u32(1) == u32(1) {
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bitset(mut output, size - i * SLOT_SIZE - j - 1)
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output.setbit(size - i * SLOT_SIZE - j - 1)
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}
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}
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}
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bits_in_last_input_slot := (size - 1) % SLOT_SIZE + 1
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for j in 0..bits_in_last_input_slot {
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if u32(instance.field[bitnslots - 1] >> u32(j)) & u32(1) == u32(1) {
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bitset(mut output, bits_in_last_input_slot - j - 1)
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output.setbit(bits_in_last_input_slot - j - 1)
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}
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}
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return output
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}
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// resize changes the size of the bit array to 'new_size'
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// resize changes the size of the bit array to 'new_size'.
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pub fn (instance mut BitField) resize(new_size int) {
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new_bitnslots := bitnslots(new_size)
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old_size := instance.size
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@ -476,13 +406,12 @@ pub fn (instance mut BitField) resize(new_size int) {
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instance.field = field.clone()
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instance.size = new_size
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if new_size < old_size && new_size % SLOT_SIZE != 0 {
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cleartail(mut instance)
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instance.cleartail()
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}
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}
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// rotate(offset int) circular-shift the bits by 'offset' positions (move
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// 'offset' bit to 0, 'offset+1' bit to 1, and so on)
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// rotate circular-shifts the bits by 'offset' positions (move
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// 'offset' bit to 0, 'offset+1' bit to 1, and so on).
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pub fn (instance BitField) rotate(offset int) BitField {
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/**
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* This function "cuts" the bitfield into two and swaps them.
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@ -506,3 +435,36 @@ pub fn (instance BitField) rotate(offset int) BitField {
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output := join(second_chunk, first_chunk)
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return output
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}
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// Internal functions
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fn (instance mut BitField) cleartail() {
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tail := instance.size % SLOT_SIZE
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if tail != 0 {
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// create a mask for the tail
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mask := u32((1 << tail) - 1)
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// clear the extra bits
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instance.field[bitnslots(instance.size) - 1] = instance.field[bitnslots(instance.size) - 1] & mask
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}
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}
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fn bitmask(bitnr int) u32 {
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return u32(u32(1) << u32(bitnr % SLOT_SIZE))
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}
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fn bitslot(size int) int {
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return size / SLOT_SIZE
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}
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fn min(input1 int, input2 int) int {
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if input1 < input2 {
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return input1
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}
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else {
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return input2
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}
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}
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fn bitnslots(length int) int {
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return (length - 1) / SLOT_SIZE + 1
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}
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@ -54,9 +54,9 @@ fn test_clone_cmp() {
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input.setbit(i)
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}
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}
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output := bitfield.clone(input)
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output := input.clone()
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assert output.getsize() == len
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assert bitfield.cmp(input, output) == true
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assert input.cmp(output) == true
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}
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fn test_slice_join() {
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@ -75,7 +75,7 @@ fn test_slice_join() {
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chunk2 := input.slice(point, input.getsize())
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// concatenate them back into one and compare to the original
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output := bitfield.join(chunk1, chunk2)
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if !bitfield.cmp(input, output) {
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if !input.cmp(output) {
|
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result = 0
|
||||
}
|
||||
}
|
||||
|
|
@ -137,7 +137,7 @@ fn test_bf_from_bytes() {
|
|||
assert result == 1
|
||||
}
|
||||
|
||||
fn test_bf_from_string() {
|
||||
fn test_bf_from_str() {
|
||||
rand.seed(time.now().unix)
|
||||
len := 80
|
||||
mut input := ''
|
||||
|
|
@ -149,7 +149,7 @@ fn test_bf_from_string() {
|
|||
input = input + '0'
|
||||
}
|
||||
}
|
||||
output := bitfield.from_string(input)
|
||||
output := bitfield.from_str(input)
|
||||
mut result := 1
|
||||
for i in 0..len {
|
||||
if input[i] != output.getbit(i) + 48 {
|
||||
|
|
@ -229,7 +229,7 @@ fn test_bf_reverse() {
|
|||
input.setbit(i)
|
||||
}
|
||||
}
|
||||
check := bitfield.clone(input)
|
||||
check := input.clone()
|
||||
output := input.reverse()
|
||||
mut result := 1
|
||||
for i in 0..len {
|
||||
|
|
@ -279,7 +279,7 @@ fn test_bf_pos() {
|
|||
needle.setbit(r)
|
||||
|
||||
// create the haystack, make sure it contains the needle
|
||||
mut haystack := bitfield.clone(needle)
|
||||
mut haystack := needle.clone()
|
||||
|
||||
// if there is space between the start of the haystack and the sought needle, fill it with zeroes
|
||||
if j > 0 {
|
||||
|
|
|
|||
Loading…
Reference in New Issue