From a074364c3731d66b56d988c8a6c960a83ea0e0a1 Mon Sep 17 00:00:00 2001 From: tmk Date: Fri, 10 Apr 2015 01:32:04 +0900 Subject: Squashed 'tmk_core/' content from commit 05caacc git-subtree-dir: tmk_core git-subtree-split: 05caaccec92694bb24c8c3c3a9940b96efd4605c --- common/util.c | 101 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 101 insertions(+) create mode 100644 common/util.c (limited to 'common/util.c') diff --git a/common/util.c b/common/util.c new file mode 100644 index 0000000000..7e0d542993 --- /dev/null +++ b/common/util.c @@ -0,0 +1,101 @@ +/* +Copyright 2011 Jun Wako + +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 . +*/ + +#include "util.h" + +// bit population - return number of on-bit +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 +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; +} + + + +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; +} -- cgit v1.2.3