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Abstracted bits out

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This commit is contained in:
Wijnand Modderman-Lenstra 2015-12-09 00:10:08 +01:00
parent f4c8a1570d
commit cdaad978da
2 changed files with 36 additions and 17 deletions
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20
bit/bit.go Normal file
View file

@ -0,0 +1,20 @@
package bit
type Bit byte
func (b *Bit) Flip() {
(*b) ^= 0x01
}
type Bits []Bit
func (bits *Bits) Bytes() []byte {
var l = len(*bits)
var o = make([]byte, (l+7)/8)
for i, b := range *bits {
if b == 0x01 {
o[i/8] |= (1 << byte(7-(i%8)))
}
}
return o
}

33
bptc/bptc.go
View file

@ -4,11 +4,10 @@ package bptc
import (
"errors"
"fmt"
"pd0mz/go-dmr/bit"
)
type Bit byte
type vector [4]Bit
type vector [4]bit.Bit
// hamming(15, 11, 3) checking of a matrix row (15 total bits, 11 data bits,
// min. distance: 3) See page 135 of the DMR Air Interface protocol
@ -20,7 +19,7 @@ type vector [4]Bit
// resulting row bits together with the corresponding parity check bit. The xor
// result (error vector) should be 0, if it's not, it can be used to determine
// the location of the erroneous bit using the generator matrix (P).
func hamming_15_11_3_parity(data []Bit, errorVector *vector) {
func hamming_15_11_3_parity(data bit.Bits, errorVector *vector) {
if data == nil || len(data) < 11 || errorVector == nil {
return
}
@ -32,7 +31,7 @@ func hamming_15_11_3_parity(data []Bit, errorVector *vector) {
e[3] = (data[0] ^ data[1] ^ data[2] ^ data[4] ^ data[6] ^ data[7] ^ data[10])
}
func hamming_15_11_3_check(data []Bit, errorVector *vector) bool {
func hamming_15_11_3_check(data bit.Bits, errorVector *vector) bool {
if data == nil || len(data) < 15 || errorVector == nil {
return false
}
@ -48,7 +47,7 @@ func hamming_15_11_3_check(data []Bit, errorVector *vector) bool {
return e[0] == 0 && e[1] == 0 && e[2] == 0 && e[3] == 0
}
func hamming_13_9_3_parity(data []Bit, errorVector *vector) {
func hamming_13_9_3_parity(data bit.Bits, errorVector *vector) {
if data == nil || len(data) < 9 || errorVector == nil {
return
}
@ -62,7 +61,7 @@ func hamming_13_9_3_parity(data []Bit, errorVector *vector) {
// hamming(13, 9, 3) checking of a matrix column (13 total bits, 9 data bits,
// min. distance: 3)
func hamming_13_9_3_check(data []Bit, errorVector *vector) bool {
func hamming_13_9_3_check(data bit.Bits, errorVector *vector) bool {
if data == nil || len(data) < 13 || errorVector == nil {
return false
}
@ -78,7 +77,7 @@ func hamming_13_9_3_check(data []Bit, errorVector *vector) bool {
return e[0] == 0 && e[1] == 0 && e[2] == 0 && e[3] == 0
}
var hamming_15_11_generator_matrix = []Bit{
var hamming_15_11_generator_matrix = bit.Bits{
1, 0, 0, 1,
1, 1, 0, 1,
1, 1, 1, 1,
@ -113,7 +112,7 @@ func hamming_15_11_3_error_position(errorVector *vector) int {
return -1
}
var hamming_13_9_generator_matrix = []Bit{
var hamming_13_9_generator_matrix = bit.Bits{
1, 1, 1, 1,
1, 1, 1, 0,
0, 1, 1, 1,
@ -146,7 +145,7 @@ func hamming_13_9_3_error_position(errorVector *vector) int {
return -1
}
func Dump(bits []Bit) {
func Dump(bits bit.Bits) {
if len(bits) != 196 {
return
}
@ -173,13 +172,13 @@ func Dump(bits []Bit) {
}
}
func CheckAndRepair(bits []Bit) (bool, error) {
func CheckAndRepair(bits bit.Bits) (bool, error) {
if bits == nil || len(bits) != 196 {
return false, errors.New("expected 196 input bits")
}
var (
cb = make([]Bit, 13)
cb = make([]bit.Bit, 13)
errorVector = vector{}
)
for col := 0; col < 15; col++ {
@ -227,8 +226,8 @@ func CheckAndRepair(bits []Bit) (bool, error) {
}
// Extract the data bits from the given deinterleaved info bits array (discards BPTC bits).
func Extract(bits []Bit) []Bit {
var e = make([]Bit, 96)
func Extract(bits bit.Bits) bit.Bits {
var e = make([]bit.Bit, 96)
copy(e[0:8], bits[4:12])
copy(e[8:19], bits[16:27])
copy(e[19:30], bits[31:42])
@ -242,11 +241,11 @@ func Extract(bits []Bit) []Bit {
}
// New BPTC(196, 96) payload from 96 data bits.
func New(bits []Bit) []Bit {
func New(bits bit.Bits) bit.Bits {
var (
dbp int
errorVector = vector{}
p = make([]Bit, 196)
p = make([]bit.Bit, 196)
)
for row := 0; row < 9; row++ {
@ -272,7 +271,7 @@ func New(bits []Bit) []Bit {
}
for col := 0; col < 15; col++ {
var cb = make([]Bit, 9)
var cb = make([]bit.Bit, 9)
for row := 0; row < 9; row++ {
cb[row] = bits[col+row*15+1]
}