-/* Functions and types for CRC checks.
- *
- * Generated on Wed Sep 21 22:30:11 2011,
- * by pycrc v0.7.8, http://www.tty1.net/pycrc/
- * using the configuration:
- * Width = 15
- * Poly = 0x4599
- * XorIn = 0x0000
- * ReflectIn = False
- * XorOut = 0x0000
- * ReflectOut = False
- * Algorithm = table-driven
- *****************************************************************************/
-typedef uint16_t crc_t;
-
-static const crc_t crc_table[2] = {
- 0x0000, 0x4599
-};
-
-crc_t crc_update(crc_t crc, uint32_t data, size_t bit_len)
-{
- unsigned int tbl_idx;
-/* crc_t bc = crc; */
-/* uint32_t bd = data; */
-/* size_t bl = bit_len; */
-
- while (bit_len--) {
- tbl_idx = (crc >> 14) ^ (data >> 31);
- crc = crc_table[tbl_idx & 0x01] ^ (crc << 1);
- data <<= 1;
- }
- crc = crc & 0x7fff;
-/* printf("crc: 0x%04x -> 0x%04x data: 0x%08x len: %d\n", */
-/* bc, crc, bd, bl); */
- return crc;
-}
-
-uint32_t calc_bitmap_crc(uint32_t *bitmap, unsigned start, unsigned end)
-{
- crc_t crc = 0;
- crc = crc_update(crc, bitmap[0] << start, 32 - start);
- crc = crc_update(crc, bitmap[1], 32);
- crc = crc_update(crc, bitmap[2], end - 64 > 32 ? 32 : end - 64);
- crc = crc_update(crc, bitmap[3], end > 96 ? end - 96 : 0);
- return (uint32_t)htons(crc << 17);
-}
-
-void write_crc_to_bitmap(uint32_t crc, uint32_t *bitmap, struct can_frame *frame)
-{
- unsigned index = frame->can_id & CAN_EFF_FLAG ? 2 : 1;
- if (frame->can_dlc < 4)
- bitmap[index] |= crc >> (frame->can_dlc*8);
- if (frame->can_dlc == 3)
- bitmap[index + 1] |= crc << 8;
- if (frame->can_dlc >= 4 && frame->can_dlc < 8)
- {
- bitmap[index + 1] |= crc >> (frame->can_dlc*8);
- if (frame->can_dlc == 7)
- bitmap[index + 2] = crc << 8;
- }
- else if (frame->can_dlc == 8)
- bitmap[index + 2] = crc;
-}
-
-unsigned calc_stuff_bits(struct can_frame *frame) {
- uint32_t bitmap[4];
- unsigned start = 0, end;
- uint32_t mask, ones = 0, basemask = 0xf8000000;
- unsigned stuffed = 0;
- memset(bitmap, 0, sizeof(bitmap));
- uint32_t crc;
-
-/* char received[64]; */
-/* sprint_canframe(received, frame, true); */
-/* printf("Frame: %s\n", received); */
-
- if (frame->can_id & CAN_EFF_FLAG) {
- // bit 31 0
- // [0] |...........................sBBBB| s = SOF, B = Base ID (11 bits)
- // [1] |BBBBBBBSIEEEEEEEEEEEEEEEEEER10DLC4| S = SRR, I = IDE, E = Extended ID (18 bits), DLC4 = DLC
- // [2] |00000000111111112222222233333333| Data bytes, MSB first
- // [3] |44444444555555556666666677777777|
- bitmap[0] =
- ((frame->can_id & CAN_EFF_MASK) >> 25);
- bitmap[1] =
- ((frame->can_id & CAN_EFF_MASK) >> 18) << 25 |
- 3 << 23 |
- ((frame->can_id & CAN_EFF_MASK) & 0x3ffff) << 7 |
- (!!(frame->can_id & CAN_RTR_FLAG)) << 6 |
- 0 << 4 |
- frame->can_dlc & 0xf;
- memcpy(&bitmap[2], &frame->data, frame->can_dlc);
- start = 27;
- end = 64 + 8*frame->can_dlc;
- } else {
- // bit 31 0
- // [0] |.............sIIIIIIIIIIIRE0DLC4| s = SOF, I = ID (11 bits), R = RTR, E = IDE, DLC4 = DLC
- // [1] |00000000111111112222222233333333| Data bytes, MSB first
- // [2] |44444444555555556666666677777777|
- bitmap[0] =
- (frame->can_id << 7) |
- (!!(frame->can_id & CAN_RTR_FLAG)) << 6 |
- 0 << 4 |
- frame->can_dlc & 0xf;
- memcpy(&bitmap[1], &frame->data, frame->can_dlc);
- start = 13;
- end = 32 + 8*frame->can_dlc;
- }
- crc = calc_bitmap_crc(bitmap, start, end);
- write_crc_to_bitmap(crc, bitmap, frame);
- end += 15;
-
- while (start < end) {
- mask = basemask >> (start & 0x1f);
- while (1) {
- ones = ones ? mask : 0;
- uint32_t chunk = (bitmap[start >> 5] & mask) ^ ones;
- //printf("start=%d bitmap=0x%08x mask=0x%08x ones=0x%08x chunk=0x%08x\n", start, bitmap[start >> 5], mask, ones, chunk);
- if (chunk) {
- unsigned change = __builtin_clz(chunk);
- start = start & ~0x1f | change;
- basemask = 0xf8000000;
- } else {
- unsigned oldstart = start;
- start += __builtin_popcount(mask);
- mask = (oldstart & 0x1f) ? basemask << (-oldstart & 0x1f) : 0;
- //printf("oldstart=%d shl=%d mask=0x%08x\n", oldstart, -oldstart & 0x1f, mask);
- if (mask && start < end)
- continue;
- if (start <= end && !mask) {
- stuffed++;
- basemask = 0xf0000000;
- //printf("stuffed %d\n", !ones);
- }
- }
- break;
- }
- ones = !ones;
- }
- //printf ("STUFFED %d BITS\n", stuffed);
- return stuffed;
-}