/* 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; }