66 lines
1.8 KiB
C++
66 lines
1.8 KiB
C++
#include <V2RFEncoding.h>
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#define V2_OFFSET(byte, key, jumpStart) ( \
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V2_OFFSETS[byte-1][key%4] \
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+ \
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((jumpStart > 0 && key >= jumpStart && key < jumpStart+0x80) ? 0x80 : 0) \
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)
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uint8_t const V2RFEncoding::V2_OFFSETS[][4] = {
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{ 0x45, 0x1F, 0x14, 0x5C }, // request type
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{ 0x2B, 0xC9, 0xE3, 0x11 }, // id 1
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{ 0x6D, 0x5F, 0x8A, 0x2B }, // id 2
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{ 0xAF, 0x03, 0x1D, 0xF3 }, // command
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{ 0x1A, 0xE2, 0xF0, 0xD1 }, // argument
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{ 0x04, 0xD8, 0x71, 0x42 }, // sequence
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{ 0xAF, 0x04, 0xDD, 0x07 }, // group
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{ 0x61, 0x13, 0x38, 0x64 } // checksum
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};
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uint8_t V2RFEncoding::xorKey(uint8_t key) {
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// Generate most significant nibble
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const uint8_t shift = (key & 0x0F) < 0x04 ? 0 : 1;
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const uint8_t x = (((key & 0xF0) >> 4) + shift + 6) % 8;
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const uint8_t msn = (((4 + x) ^ 1) & 0x0F) << 4;
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// Generate least significant nibble
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const uint8_t lsn = ((((key & 0xF) + 4)^2) & 0x0F);
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return ( msn | lsn );
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}
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uint8_t V2RFEncoding::decodeByte(uint8_t byte, uint8_t s1, uint8_t xorKey, uint8_t s2) {
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uint8_t value = byte - s2;
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value = value ^ xorKey;
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value = value - s1;
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return value;
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}
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uint8_t V2RFEncoding::encodeByte(uint8_t byte, uint8_t s1, uint8_t xorKey, uint8_t s2) {
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uint8_t value = byte + s1;
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value = value ^ xorKey;
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value = value + s2;
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return value;
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}
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void V2RFEncoding::decodeV2Packet(uint8_t *packet) {
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uint8_t key = xorKey(packet[0]);
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for (size_t i = 1; i <= 8; i++) {
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packet[i] = decodeByte(packet[i], 0, key, V2_OFFSET(i, packet[0], V2_OFFSET_JUMP_START));
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}
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}
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void V2RFEncoding::encodeV2Packet(uint8_t *packet) {
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uint8_t key = xorKey(packet[0]);
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uint8_t sum = key;
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for (size_t i = 1; i <= 7; i++) {
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sum += packet[i];
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packet[i] = encodeByte(packet[i], 0, key, V2_OFFSET(i, packet[0], V2_OFFSET_JUMP_START));
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}
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packet[8] = encodeByte(sum, 2, key, V2_OFFSET(8, packet[0], 0));
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}
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