mirror of
https://github.com/RfidResearchGroup/proxmark3.git
synced 2024-09-20 07:16:14 +08:00
commit
c7af82f146
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@ -98,39 +98,13 @@ uint8_t reflect8(uint8_t b) {
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return (b * 0x0202020202ULL & 0x010884422010ULL) % 1023;
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}
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// Reverse the bits in a byte with 4 operations (64-bit multiply, no division):
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/*
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uint8_t reflect8(uint8_t b) {
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return ((b * 0x80200802ULL) & 0x0884422110ULL) * 0x0101010101ULL >> 32;
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}
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*/
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uint16_t reflect16(uint16_t b) {
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uint16_t v = 0;
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v |= (b & 0x8000) >> 15;
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v |= (b & 0x4000) >> 13;
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v |= (b & 0x2000) >> 11;
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v |= (b & 0x1000) >> 9;
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v |= (b & 0x0800) >> 7;
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v |= (b & 0x0400) >> 5;
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v |= (b & 0x0200) >> 3;
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v |= (b & 0x0100) >> 1;
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v |= (b & 0x0080) << 1;
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v |= (b & 0x0040) << 3;
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v |= (b & 0x0020) << 5;
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v |= (b & 0x0010) << 7;
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v |= (b & 0x0008) << 9;
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v |= (b & 0x0004) << 11;
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v |= (b & 0x0002) << 13;
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v |= (b & 0x0001) << 15;
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uint16_t reflect16(uint16_t v) {
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v = (reflect8(v) << 8) | (reflect8(v >> 8) & 0xFF);
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return v;
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}
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uint32_t reflect32(uint32_t b) {
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uint32_t reflect32(uint32_t v) {
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// https://graphics.stanford.edu/~seander/bithacks.html#BitReverseTable
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uint32_t v = b; // 32-bit word to reverse bit order
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// swap odd and even bits
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v = ((v >> 1) & 0x55555555) | ((v & 0x55555555) << 1);
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// swap consecutive pairs
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@ -140,17 +114,23 @@ uint32_t reflect32(uint32_t b) {
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// swap bytes
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v = ((v >> 8) & 0x00FF00FF) | ((v & 0x00FF00FF) << 8);
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// swap 2-byte long pairs
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v = (v >> 16) | (v << 16);
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v = ( v >> 16 ) | ( v << 16);
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return v;
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}
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uint64_t reflect64(uint64_t b) {
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uint64_t reflect48(uint64_t v) {
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uint64_t vhi = reflect16(v >> 32);
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uint64_t vlo = reflect32(v);
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v = (vlo << 32) | (vhi & 0xFFFF);
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return v;
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}
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uint64_t reflect64(uint64_t v) {
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// https://graphics.stanford.edu/~seander/bithacks.html#BitReverseTable
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uint64_t v = b; // 32-bit word to reverse bit order
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// swap 2-byte long pairs
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// swap 4-byte long pairs
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uint64_t v1 = reflect32(v >> 32);
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uint64_t v2 = reflect32(v);
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v = (v1 << 32) | (v2 & 0xFFFFFFFF);
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v = (v2 << 32) | (v1 & 0xFFFFFFFF);
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return v;
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}
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@ -74,6 +74,7 @@ uint32_t reflect(uint32_t v, int b); // used in crc.c ...
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uint8_t reflect8(uint8_t b); // dedicated 8bit reversal
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uint16_t reflect16(uint16_t b); // dedicated 16bit reversal
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uint32_t reflect32(uint32_t b); // dedicated 32bit reversal
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uint64_t reflect48(uint64_t b); // dedicated 48bit reversal
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uint64_t reflect64(uint64_t b); // dedicated 64bit reversal
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void num_to_bytes(uint64_t n, size_t len, uint8_t *dest);
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