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- /*
- Copyright 2011 Jun Wako <[email protected]>
-
- 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
- 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;
- }
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