491 lines
13 KiB
C
491 lines
13 KiB
C
/*
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* Copyright 2022 Clayton Smith (argilo@gmail.com)
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*
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* This file is part of secplus.
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*
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* SPDX-License-Identifier: GPL-3.0-or-later
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*
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*/
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#include "secplus.h"
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int8_t encode_v1(const uint32_t rolling, uint32_t fixed, uint8_t *symbols1,
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uint8_t *symbols2) {
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uint32_t rolling_reversed = 0;
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int8_t i, half;
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uint8_t acc;
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uint8_t *symbols;
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if (fixed >= 3486784401u) {
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return -1;
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}
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for (i = 1; i < 32; i++) {
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rolling_reversed |= ((rolling >> i) & 1) << (32 - i - 1);
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}
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for (half = 1; half >= 0; half--) {
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symbols = (half == 0 ? symbols1 : symbols2);
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for (i = 18; i >= 0; i -= 2) {
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symbols[i] = rolling_reversed % 3;
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rolling_reversed /= 3;
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symbols[i + 1] = fixed % 3;
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fixed /= 3;
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}
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acc = 0;
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for (i = 0; i < 20; i += 2) {
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acc += symbols[i];
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acc += symbols[i + 1];
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symbols[i + 1] = acc % 3;
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}
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}
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return 0;
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}
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int8_t decode_v1(const uint8_t *symbols1, const uint8_t *symbols2,
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uint32_t *rolling, uint32_t *fixed) {
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uint32_t rolling_reversed = 0;
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uint8_t acc;
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uint8_t digit;
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int8_t i, half;
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const uint8_t *symbols;
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*rolling = 0;
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*fixed = 0;
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for (half = 0; half < 2; half++) {
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symbols = (half == 0 ? symbols1 : symbols2);
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acc = 0;
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for (i = 0; i < 20; i += 2) {
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digit = symbols[i];
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rolling_reversed = (rolling_reversed * 3) + digit;
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acc += digit;
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digit = (60 + symbols[i + 1] - acc) % 3;
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*fixed = (*fixed * 3) + digit;
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acc += digit;
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}
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}
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for (i = 0; i < 32; i++) {
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*rolling |= ((rolling_reversed >> i) & 1) << (32 - i - 1);
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}
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return 0;
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}
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static void v2_calc_parity(const uint64_t fixed, uint32_t *data) {
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uint32_t parity = (fixed >> 32) & 0xf;
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int8_t offset;
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*data &= 0xffff0fff;
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for (offset = 0; offset < 32; offset += 4) {
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parity ^= ((*data >> offset) & 0xf);
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}
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*data |= (parity << 12);
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}
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static int8_t v2_check_parity(const uint64_t fixed, const uint32_t data) {
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uint32_t parity = (fixed >> 32) & 0xf;
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int8_t offset;
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for (offset = 0; offset < 32; offset += 4) {
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parity ^= ((data >> offset) & 0xf);
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}
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if (parity != 0) {
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return -1;
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}
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return 0;
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}
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static void encode_v2_rolling(const uint32_t rolling,
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uint32_t *rolling_halves) {
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uint32_t rolling_reversed = 0;
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int8_t i, half;
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for (i = 0; i < 28; i++) {
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rolling_reversed |= ((rolling >> i) & 1) << (28 - i - 1);
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}
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rolling_halves[0] = 0;
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rolling_halves[1] = 0;
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for (half = 0; half < 2; half++) {
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for (i = 0; i < 8; i += 2) {
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rolling_halves[half] |= rolling_reversed % 3 << i;
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rolling_reversed /= 3;
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}
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}
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for (half = 0; half < 2; half++) {
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for (i = 10; i < 18; i += 2) {
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rolling_halves[half] |= rolling_reversed % 3 << i;
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rolling_reversed /= 3;
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}
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}
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rolling_halves[0] |= (rolling_reversed % 3) << 8;
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rolling_reversed /= 3;
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rolling_halves[1] |= (rolling_reversed % 3) << 8;
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}
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static int8_t decode_v2_rolling(const uint32_t *rolling_halves,
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uint32_t *rolling) {
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int8_t i, half;
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uint32_t rolling_reversed;
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rolling_reversed = (rolling_halves[1] >> 8) & 3;
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rolling_reversed = (rolling_reversed * 3) + ((rolling_halves[0] >> 8) & 3);
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for (half = 1; half >= 0; half--) {
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for (i = 16; i >= 10; i -= 2) {
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rolling_reversed =
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(rolling_reversed * 3) + ((rolling_halves[half] >> i) & 3);
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}
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}
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for (half = 1; half >= 0; half--) {
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for (i = 6; i >= 0; i -= 2) {
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rolling_reversed =
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(rolling_reversed * 3) + ((rolling_halves[half] >> i) & 3);
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}
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}
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if (rolling_reversed >= 0x10000000) {
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return -1;
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}
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*rolling = 0;
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for (i = 0; i < 28; i++) {
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*rolling |= ((rolling_reversed >> i) & 1) << (28 - i - 1);
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}
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return 0;
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}
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static int8_t v2_combine_halves(const uint8_t frame_type,
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const uint32_t *rolling_halves,
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const uint32_t *fixed_halves,
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const uint16_t *data_halves, uint32_t *rolling,
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uint64_t *fixed, uint32_t *data) {
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int8_t err = 0;
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err = decode_v2_rolling(rolling_halves, rolling);
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if (err < 0) {
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return err;
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}
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*fixed = ((uint64_t)fixed_halves[0] << 20) | fixed_halves[1];
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if (frame_type == 1) {
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*data = ((uint32_t)data_halves[0] << 16) | data_halves[1];
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err = v2_check_parity(*fixed, *data);
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if (err < 0) {
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return err;
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}
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}
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return 0;
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}
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static const int8_t ORDER[16] = {9, 33, 6, -1, 24, 18, 36, -1,
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24, 36, 6, -1, -1, -1, -1, -1};
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static const int8_t INVERT[16] = {6, 2, 1, -1, 7, 5, 3, -1,
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4, 0, 5, -1, -1, -1, -1, -1};
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static void v2_scramble(const uint32_t *parts, const uint8_t frame_type,
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uint8_t *packet_half) {
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const int8_t order = ORDER[packet_half[0] >> 4];
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const int8_t invert = INVERT[packet_half[0] & 0xf];
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int8_t i;
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uint8_t out_offset = 10;
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int8_t end;
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uint32_t parts_permuted[3];
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end = (frame_type == 0 ? 5 : 8);
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for (i = 1; i < end; i++) {
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packet_half[i] = 0;
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}
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parts_permuted[0] =
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(invert & 4) ? ~parts[(order >> 4) & 3] : parts[(order >> 4) & 3];
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parts_permuted[1] =
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(invert & 2) ? ~parts[(order >> 2) & 3] : parts[(order >> 2) & 3];
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parts_permuted[2] = (invert & 1) ? ~parts[order & 3] : parts[order & 3];
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end = (frame_type == 0 ? 8 : 0);
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for (i = 18 - 1; i >= end; i--) {
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packet_half[out_offset >> 3] |= ((parts_permuted[0] >> i) & 1)
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<< (7 - (out_offset % 8));
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out_offset++;
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packet_half[out_offset >> 3] |= ((parts_permuted[1] >> i) & 1)
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<< (7 - (out_offset % 8));
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out_offset++;
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packet_half[out_offset >> 3] |= ((parts_permuted[2] >> i) & 1)
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<< (7 - (out_offset % 8));
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out_offset++;
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}
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}
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static int8_t v2_unscramble(const uint8_t frame_type, const uint8_t indicator,
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const uint8_t *packet_half, uint32_t *parts) {
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const int8_t order = ORDER[indicator >> 4];
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const int8_t invert = INVERT[indicator & 0xf];
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int8_t i;
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uint8_t out_offset = 10;
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const int8_t end = (frame_type == 0 ? 8 : 0);
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uint32_t parts_permuted[3] = {0, 0, 0};
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if ((order == -1) || (invert == -1)) {
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return -1;
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}
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for (i = 18 - 1; i >= end; i--) {
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parts_permuted[0] |=
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(uint32_t)((packet_half[out_offset >> 3] >> (7 - (out_offset % 8))) & 1)
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<< i;
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out_offset++;
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parts_permuted[1] |=
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(uint32_t)((packet_half[out_offset >> 3] >> (7 - (out_offset % 8))) & 1)
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<< i;
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out_offset++;
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parts_permuted[2] |=
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(uint32_t)((packet_half[out_offset >> 3] >> (7 - (out_offset % 8))) & 1)
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<< i;
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out_offset++;
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}
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parts[(order >> 4) & 3] =
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(invert & 4) ? ~parts_permuted[0] : parts_permuted[0];
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parts[(order >> 2) & 3] =
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(invert & 2) ? ~parts_permuted[1] : parts_permuted[1];
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parts[order & 3] = (invert & 1) ? ~parts_permuted[2] : parts_permuted[2];
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return 0;
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}
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static void encode_v2_half_parts(const uint32_t rolling, const uint32_t fixed,
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const uint16_t data, const uint8_t frame_type,
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uint8_t *packet_half) {
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uint32_t parts[3];
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parts[0] = ((fixed >> 10) << 8) | (data >> 8);
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parts[1] = ((fixed & 0x3ff) << 8) | (data & 0xff);
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parts[2] = rolling;
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packet_half[0] = (uint8_t)rolling;
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v2_scramble(parts, frame_type, packet_half);
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}
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static int8_t decode_v2_half_parts(const uint8_t frame_type,
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const uint8_t indicator,
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const uint8_t *packet_half,
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uint32_t *rolling, uint32_t *fixed,
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uint16_t *data) {
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int8_t err = 0;
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int8_t i;
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uint32_t parts[3];
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err = v2_unscramble(frame_type, indicator, packet_half, parts);
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if (err < 0) {
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return err;
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}
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if ((frame_type == 1) && ((parts[2] & 0xff) != indicator)) {
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return -1;
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}
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for (i = 8; i < 18; i += 2) {
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if (((parts[2] >> i) & 3) == 3) {
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return -1;
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}
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}
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*rolling = (parts[2] & 0x3ff00) | indicator;
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*fixed = ((parts[0] & 0x3ff00) << 2) | ((parts[1] & 0x3ff00) >> 8);
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*data = ((parts[0] & 0xff) << 8) | (parts[1] & 0xff);
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return 0;
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}
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static int8_t v2_check_limits(const uint32_t rolling, const uint64_t fixed) {
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if ((rolling >> 28) != 0) {
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return -1;
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}
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if ((fixed >> 40) != 0) {
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return -1;
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}
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return 0;
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}
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static void encode_v2_half(const uint32_t rolling, const uint32_t fixed,
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const uint16_t data, const uint8_t frame_type,
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uint8_t *packet_half) {
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encode_v2_half_parts(rolling, fixed, data, frame_type, packet_half);
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/* shift indicator two bits to the right */
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packet_half[1] |= (packet_half[0] & 0x3) << 6;
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packet_half[0] >>= 2;
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/* set frame type */
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packet_half[0] |= (frame_type << 6);
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}
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int8_t encode_v2(const uint32_t rolling, const uint64_t fixed, uint32_t data,
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const uint8_t frame_type, uint8_t *packet1, uint8_t *packet2) {
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int8_t err = 0;
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uint32_t rolling_halves[2];
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err = v2_check_limits(rolling, fixed);
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if (err < 0) {
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return err;
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}
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encode_v2_rolling(rolling, rolling_halves);
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v2_calc_parity(fixed, &data);
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encode_v2_half(rolling_halves[0], fixed >> 20, data >> 16, frame_type,
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packet1);
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encode_v2_half(rolling_halves[1], fixed & 0xfffff, data & 0xffff, frame_type,
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packet2);
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return 0;
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}
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static int8_t decode_v2_half(const uint8_t frame_type,
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const uint8_t *packet_half, uint32_t *rolling,
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uint32_t *fixed, uint16_t *data) {
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int8_t err = 0;
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const uint8_t indicator = (packet_half[0] << 2) | (packet_half[1] >> 6);
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if ((packet_half[0] >> 6) != frame_type) {
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return -1;
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}
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err = decode_v2_half_parts(frame_type, indicator, packet_half, rolling, fixed,
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data);
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if (err < 0) {
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return err;
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}
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return 0;
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}
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int8_t decode_v2(uint8_t frame_type, const uint8_t *packet1,
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const uint8_t *packet2, uint32_t *rolling, uint64_t *fixed,
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uint32_t *data) {
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int8_t err = 0;
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uint32_t rolling_halves[2];
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uint32_t fixed_halves[2];
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uint16_t data_halves[2];
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err = decode_v2_half(frame_type, packet1, &rolling_halves[0],
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&fixed_halves[0], &data_halves[0]);
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if (err < 0) {
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return err;
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}
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err = decode_v2_half(frame_type, packet2, &rolling_halves[1],
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&fixed_halves[1], &data_halves[1]);
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if (err < 0) {
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return err;
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}
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err = v2_combine_halves(frame_type, rolling_halves, fixed_halves, data_halves,
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rolling, fixed, data);
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if (err < 0) {
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return err;
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}
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return 0;
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}
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static void encode_wireline_half(const uint32_t rolling, const uint32_t fixed,
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const uint16_t data, uint8_t *packet_half) {
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encode_v2_half_parts(rolling, fixed, data, 1, packet_half);
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}
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int8_t encode_wireline(const uint32_t rolling, const uint64_t fixed,
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uint32_t data, uint8_t *packet) {
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int8_t err = 0;
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uint32_t rolling_halves[2];
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err = v2_check_limits(rolling, fixed);
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if (err < 0) {
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return err;
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}
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encode_v2_rolling(rolling, rolling_halves);
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v2_calc_parity(fixed, &data);
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packet[0] = 0x55;
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packet[1] = 0x01;
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packet[2] = 0x00;
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encode_wireline_half(rolling_halves[0], fixed >> 20, data >> 16, &packet[3]);
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encode_wireline_half(rolling_halves[1], fixed & 0xfffff, data & 0xffff,
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&packet[11]);
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return 0;
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}
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static int8_t decode_wireline_half(const uint8_t *packet_half,
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uint32_t *rolling, uint32_t *fixed,
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uint16_t *data) {
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int8_t err = 0;
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const uint8_t indicator = packet_half[0];
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if ((packet_half[1] >> 6) != 0) {
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return -1;
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}
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err = decode_v2_half_parts(1, indicator, packet_half, rolling, fixed, data);
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if (err < 0) {
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return err;
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}
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return 0;
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}
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int8_t decode_wireline(const uint8_t *packet, uint32_t *rolling,
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uint64_t *fixed, uint32_t *data) {
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int8_t err = 0;
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uint32_t rolling_halves[2];
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uint32_t fixed_halves[2];
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uint16_t data_halves[2];
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if ((packet[0] != 0x55) || (packet[1] != 0x01) || (packet[2] != 0x00)) {
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return -1;
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}
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err = decode_wireline_half(&packet[3], &rolling_halves[0], &fixed_halves[0],
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&data_halves[0]);
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if (err < 0) {
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return err;
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}
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err = decode_wireline_half(&packet[11], &rolling_halves[1], &fixed_halves[1],
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&data_halves[1]);
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if (err < 0) {
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return err;
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}
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err = v2_combine_halves(1, rolling_halves, fixed_halves, data_halves, rolling,
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fixed, data);
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if (err < 0) {
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return err;
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}
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return 0;
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}
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