123 lines
2.8 KiB
C
123 lines
2.8 KiB
C
/*
|
|
Copyright 2011 Jun Wako <wakojun@gmail.com>
|
|
|
|
This program is free software: you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation, either version 2 of the License, or
|
|
(at your option) any later version.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#include "util.h"
|
|
|
|
// bit population - return number of on-bit
|
|
__attribute__((noinline)) uint8_t bitpop(uint8_t bits) {
|
|
uint8_t c;
|
|
for (c = 0; bits; c++) bits &= bits - 1;
|
|
return c;
|
|
/*
|
|
const uint8_t bit_count[] = { 0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4 };
|
|
return bit_count[bits>>4] + bit_count[bits&0x0F]
|
|
*/
|
|
}
|
|
|
|
uint8_t bitpop16(uint16_t bits) {
|
|
uint8_t c;
|
|
for (c = 0; bits; c++) bits &= bits - 1;
|
|
return c;
|
|
}
|
|
|
|
uint8_t bitpop32(uint32_t bits) {
|
|
uint8_t c;
|
|
for (c = 0; bits; c++) bits &= bits - 1;
|
|
return c;
|
|
}
|
|
|
|
// most significant on-bit - return highest location of on-bit
|
|
// NOTE: return 0 when bit0 is on or all bits are off
|
|
__attribute__((noinline)) uint8_t biton(uint8_t bits) {
|
|
uint8_t n = 0;
|
|
if (bits >> 4) {
|
|
bits >>= 4;
|
|
n += 4;
|
|
}
|
|
if (bits >> 2) {
|
|
bits >>= 2;
|
|
n += 2;
|
|
}
|
|
if (bits >> 1) {
|
|
bits >>= 1;
|
|
n += 1;
|
|
}
|
|
return n;
|
|
}
|
|
|
|
uint8_t biton16(uint16_t bits) {
|
|
uint8_t n = 0;
|
|
if (bits >> 8) {
|
|
bits >>= 8;
|
|
n += 8;
|
|
}
|
|
if (bits >> 4) {
|
|
bits >>= 4;
|
|
n += 4;
|
|
}
|
|
if (bits >> 2) {
|
|
bits >>= 2;
|
|
n += 2;
|
|
}
|
|
if (bits >> 1) {
|
|
bits >>= 1;
|
|
n += 1;
|
|
}
|
|
return n;
|
|
}
|
|
|
|
uint8_t biton32(uint32_t bits) {
|
|
uint8_t n = 0;
|
|
if (bits >> 16) {
|
|
bits >>= 16;
|
|
n += 16;
|
|
}
|
|
if (bits >> 8) {
|
|
bits >>= 8;
|
|
n += 8;
|
|
}
|
|
if (bits >> 4) {
|
|
bits >>= 4;
|
|
n += 4;
|
|
}
|
|
if (bits >> 2) {
|
|
bits >>= 2;
|
|
n += 2;
|
|
}
|
|
if (bits >> 1) {
|
|
bits >>= 1;
|
|
n += 1;
|
|
}
|
|
return n;
|
|
}
|
|
|
|
__attribute__((noinline)) uint8_t bitrev(uint8_t bits) {
|
|
bits = (bits & 0x0f) << 4 | (bits & 0xf0) >> 4;
|
|
bits = (bits & 0b00110011) << 2 | (bits & 0b11001100) >> 2;
|
|
bits = (bits & 0b01010101) << 1 | (bits & 0b10101010) >> 1;
|
|
return bits;
|
|
}
|
|
|
|
uint16_t bitrev16(uint16_t bits) {
|
|
bits = bitrev(bits & 0x00ff) << 8 | bitrev((bits & 0xff00) >> 8);
|
|
return bits;
|
|
}
|
|
|
|
uint32_t bitrev32(uint32_t bits) {
|
|
bits = (uint32_t)bitrev16(bits & 0x0000ffff) << 16 | bitrev16((bits & 0xffff0000) >> 16);
|
|
return bits;
|
|
}
|