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adapt reflect8 fct

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iceman1001 2020-07-06 05:42:10 +02:00
commit 791afef728
1 changed files with 15 additions and 0 deletions
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15
common/commonutil.c
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@ -60,9 +60,21 @@ uint32_t reflect(uint32_t v, int b) {
return v; return v;
} }
// https://graphics.stanford.edu/~seander/bithacks.html#BitReverseTable
// Reverse the bits in a byte with 3 operations (64-bit multiply and modulus division):
uint8_t reflect8(uint8_t b) {
return (b * 0x0202020202ULL & 0x010884422010ULL) % 1023;
}
// Reverse the bits in a byte with 4 operations (64-bit multiply, no division):
/*
uint8_t reflect8(uint8_t b) { uint8_t reflect8(uint8_t b) {
return ((b * 0x80200802ULL) & 0x0884422110ULL) * 0x0101010101ULL >> 32; return ((b * 0x80200802ULL) & 0x0884422110ULL) * 0x0101010101ULL >> 32;
} }
*/
uint16_t reflect16(uint16_t b) { uint16_t reflect16(uint16_t b) {
uint16_t v = 0; uint16_t v = 0;
v |= (b & 0x8000) >> 15; v |= (b & 0x8000) >> 15;
@ -117,10 +129,13 @@ void lsl(uint8_t *data, size_t len) {
data[len - 1] <<= 1; data[len - 1] <<= 1;
} }
// BSWAP24 of array[3]
uint32_t le24toh(uint8_t data[3]) { uint32_t le24toh(uint8_t data[3]) {
return (data[2] << 16) | (data[1] << 8) | data[0]; return (data[2] << 16) | (data[1] << 8) | data[0];
} }
// BSWAP24, take u32, output array
void htole24(uint32_t val, uint8_t data[3]) { void htole24(uint32_t val, uint8_t data[3]) {
data[0] = (uint8_t) val; data[0] = (uint8_t) val;
data[1] = (uint8_t)(val >> 8); data[1] = (uint8_t)(val >> 8);