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90 lines
2.3 KiB
C
90 lines
2.3 KiB
C
//-----------------------------------------------------------------------------
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// Jonathan Westhues, Sept 2005
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//
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// This code is licensed to you under the terms of the GNU GPL, version 2 or,
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// at your option, any later version. See the LICENSE.txt file for the text of
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// the license.
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//-----------------------------------------------------------------------------
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// Utility functions used in many places, not specific to any piece of code.
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//-----------------------------------------------------------------------------
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#include "commonutil.h"
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/*
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ref http://www.csm.ornl.gov/~dunigan/crc.html
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Returns the value v with the bottom b [0,32] bits reflected.
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Example: reflect(0x3e23L,3) == 0x3e26
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*/
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uint32_t reflect(uint32_t v, int b) {
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uint32_t t = v;
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for (int i = 0; i < b; ++i) {
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if (t & 1)
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v |= BITMASK((b - 1) - i);
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else
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v &= ~BITMASK((b - 1) - i);
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t >>= 1;
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}
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return v;
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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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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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return v;
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}
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void num_to_bytes(uint64_t n, size_t len, uint8_t *dest) {
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while (len--) {
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dest[len] = (uint8_t) n;
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n >>= 8;
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}
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}
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uint64_t bytes_to_num(uint8_t *src, size_t len) {
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uint64_t num = 0;
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while (len--) {
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num = (num << 8) | (*src);
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src++;
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}
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return num;
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}
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// RotateLeft - Ultralight, Desfire
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void rol(uint8_t *data, const size_t len) {
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uint8_t first = data[0];
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for (size_t i = 0; i < len - 1; i++) {
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data[i] = data[i + 1];
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}
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data[len - 1] = first;
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}
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void lsl(uint8_t *data, size_t len) {
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for (size_t n = 0; n < len - 1; n++) {
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data[n] = (data[n] << 1) | (data[n + 1] >> 7);
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}
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data[len - 1] <<= 1;
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}
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int32_t le24toh(uint8_t data[3]) {
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return (data[2] << 16) | (data[1] << 8) | data[0];
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}
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