-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));
- crc_t crc = 0;
- uint32_t crcx;
-
-/* char received[64]; */
-/* sprint_canframe(received, frame, true); */
-/* printf("Frame: %s\n", received); */
-
- if (frame->can_id & CAN_EFF_FLAG) {
- 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;
- bitmap[2] = htonl(((uint32_t*)frame->data)[0]);
- bitmap[3] = htonl(((uint32_t*)frame->data)[1]);
- start = 27;
- end = 64 + 8*frame->can_dlc;
- 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);
- crcx = (uint32_t)htons(crc) << 17;
- if (frame->can_dlc < 4)
- bitmap[2] |= crcx >> (frame->can_dlc*8);
- if (frame->can_dlc = 3)
- bitmap[3] |= crcx << 8;
- if (frame->can_dlc >= 4)
- bitmap[3] |= crcx >> (frame->can_dlc*8);
- } else {
- bitmap[0] =
- (frame->can_id << 7) |
- (!!(frame->can_id & CAN_RTR_FLAG)) << 6 |
- 0 << 4 |
- frame->can_dlc & 0xf;
- bitmap[1] = htonl(((uint32_t*)frame->data)[0]);
- bitmap[2] = htonl(((uint32_t*)frame->data)[1]);
- start = 13;
- end = 32 + 8*frame->can_dlc;
- }
- /* TODO: Calc stuff bits in CRC */
- 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;
-}