--- /dev/null
+/*
+ * canframelen.c
+ *
+ * Copyright (c) 2013, 2014 Czech Technical University in Prague
+ *
+ * Author: Michal Sojka <sojkam1@fel.cvut.cz>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Czech Technical University in Prague nor the
+ * names of its contributors may be used to endorse or promote
+ * products derived from this software without specific prior
+ * written permission.
+ *
+ * Alternatively, provided that this notice is retained in full, this
+ * software may be distributed under the terms of the GNU General
+ * Public License ("GPL") version 2, in which case the provisions of the
+ * GPL apply INSTEAD OF those given above.
+ *
+ * The provided data structures and external interfaces from this code
+ * are not restricted to be used by modules with a GPL compatible license.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * Send feedback to <linux-can@vger.kernel.org>
+ *
+ */
+
+#include "canframelen.h"
+#include <stdint.h>
+#include <stddef.h>
+#include <stdbool.h>
+#include <string.h>
+#include <assert.h>
+#include <arpa/inet.h>
+
+/**
+ * Functions and types for CRC checks.
+ *
+ * Generated on Wed Jan 8 15:14:20 2014,
+ * by pycrc v0.8.1, 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 table used for the table_driven implementation.
+ *****************************************************************************/
+static const crc_t crc_table[256] = {
+ 0x0000, 0x4599, 0x4eab, 0x0b32, 0x58cf, 0x1d56, 0x1664, 0x53fd, 0x7407, 0x319e, 0x3aac, 0x7f35, 0x2cc8, 0x6951, 0x6263, 0x27fa,
+ 0x2d97, 0x680e, 0x633c, 0x26a5, 0x7558, 0x30c1, 0x3bf3, 0x7e6a, 0x5990, 0x1c09, 0x173b, 0x52a2, 0x015f, 0x44c6, 0x4ff4, 0x0a6d,
+ 0x5b2e, 0x1eb7, 0x1585, 0x501c, 0x03e1, 0x4678, 0x4d4a, 0x08d3, 0x2f29, 0x6ab0, 0x6182, 0x241b, 0x77e6, 0x327f, 0x394d, 0x7cd4,
+ 0x76b9, 0x3320, 0x3812, 0x7d8b, 0x2e76, 0x6bef, 0x60dd, 0x2544, 0x02be, 0x4727, 0x4c15, 0x098c, 0x5a71, 0x1fe8, 0x14da, 0x5143,
+ 0x73c5, 0x365c, 0x3d6e, 0x78f7, 0x2b0a, 0x6e93, 0x65a1, 0x2038, 0x07c2, 0x425b, 0x4969, 0x0cf0, 0x5f0d, 0x1a94, 0x11a6, 0x543f,
+ 0x5e52, 0x1bcb, 0x10f9, 0x5560, 0x069d, 0x4304, 0x4836, 0x0daf, 0x2a55, 0x6fcc, 0x64fe, 0x2167, 0x729a, 0x3703, 0x3c31, 0x79a8,
+ 0x28eb, 0x6d72, 0x6640, 0x23d9, 0x7024, 0x35bd, 0x3e8f, 0x7b16, 0x5cec, 0x1975, 0x1247, 0x57de, 0x0423, 0x41ba, 0x4a88, 0x0f11,
+ 0x057c, 0x40e5, 0x4bd7, 0x0e4e, 0x5db3, 0x182a, 0x1318, 0x5681, 0x717b, 0x34e2, 0x3fd0, 0x7a49, 0x29b4, 0x6c2d, 0x671f, 0x2286,
+ 0x2213, 0x678a, 0x6cb8, 0x2921, 0x7adc, 0x3f45, 0x3477, 0x71ee, 0x5614, 0x138d, 0x18bf, 0x5d26, 0x0edb, 0x4b42, 0x4070, 0x05e9,
+ 0x0f84, 0x4a1d, 0x412f, 0x04b6, 0x574b, 0x12d2, 0x19e0, 0x5c79, 0x7b83, 0x3e1a, 0x3528, 0x70b1, 0x234c, 0x66d5, 0x6de7, 0x287e,
+ 0x793d, 0x3ca4, 0x3796, 0x720f, 0x21f2, 0x646b, 0x6f59, 0x2ac0, 0x0d3a, 0x48a3, 0x4391, 0x0608, 0x55f5, 0x106c, 0x1b5e, 0x5ec7,
+ 0x54aa, 0x1133, 0x1a01, 0x5f98, 0x0c65, 0x49fc, 0x42ce, 0x0757, 0x20ad, 0x6534, 0x6e06, 0x2b9f, 0x7862, 0x3dfb, 0x36c9, 0x7350,
+ 0x51d6, 0x144f, 0x1f7d, 0x5ae4, 0x0919, 0x4c80, 0x47b2, 0x022b, 0x25d1, 0x6048, 0x6b7a, 0x2ee3, 0x7d1e, 0x3887, 0x33b5, 0x762c,
+ 0x7c41, 0x39d8, 0x32ea, 0x7773, 0x248e, 0x6117, 0x6a25, 0x2fbc, 0x0846, 0x4ddf, 0x46ed, 0x0374, 0x5089, 0x1510, 0x1e22, 0x5bbb,
+ 0x0af8, 0x4f61, 0x4453, 0x01ca, 0x5237, 0x17ae, 0x1c9c, 0x5905, 0x7eff, 0x3b66, 0x3054, 0x75cd, 0x2630, 0x63a9, 0x689b, 0x2d02,
+ 0x276f, 0x62f6, 0x69c4, 0x2c5d, 0x7fa0, 0x3a39, 0x310b, 0x7492, 0x5368, 0x16f1, 0x1dc3, 0x585a, 0x0ba7, 0x4e3e, 0x450c, 0x0095
+};
+
+/**
+ * Update the crc value with new data.
+ *
+ * \param crc The current crc value.
+ * \param data Pointer to a buffer of \a data_len bytes.
+ * \param data_len Number of bytes in the \a data buffer.
+ * \return The updated crc value.
+ *****************************************************************************/
+static crc_t crc_update_bytewise(crc_t crc, const unsigned char *data, size_t data_len)
+{
+ unsigned int tbl_idx;
+
+ while (data_len--) {
+ tbl_idx = ((crc >> 7) ^ *data) & 0xff;
+ crc = (crc_table[tbl_idx] ^ (crc << 8)) & 0x7fff;
+
+ data++;
+ }
+ return crc & 0x7fff;
+}
+
+/**
+ * Update the crc value with new data.
+ *
+ * \param crc The current crc value.
+ * \param data Data value
+ * \param bits The number of most significant bits in data used for CRC calculation
+ * \return The updated crc value.
+ *****************************************************************************/
+static crc_t crc_update_bitwise(crc_t crc, uint8_t data, size_t bits)
+{
+ uint8_t i;
+ bool bit;
+
+ for (i = 0x80; bits--; i >>= 1) {
+ bit = crc & 0x4000;
+ if (data & i) {
+ bit = !bit;
+ }
+ crc <<= 1;
+ if (bit) {
+ crc ^= 0x4599;
+ }
+ }
+ return crc & 0x7fff;
+}
+
+static crc_t calc_bitmap_crc(uint8_t *bitmap, unsigned start, unsigned end)
+{
+ crc_t crc = 0;
+
+ if (start % 8) {
+ crc = crc_update_bitwise(crc, bitmap[start / 8] << (start % 8), 8 - start % 8);
+ start += 8 - start % 8;
+ }
+ crc = crc_update_bytewise(crc, &bitmap[start / 8], (end - start) / 8);
+ crc = crc_update_bitwise(crc, bitmap[end / 8], end % 8);
+ return crc;
+}
+
+static unsigned cfl_exact(struct can_frame *frame)
+{
+ uint8_t bitmap[16];
+ unsigned start = 0, end;
+ crc_t crc;
+ uint16_t crc_be;
+ uint8_t mask, lookfor;
+ unsigned i, stuffed;
+ const int8_t clz[32] = /* count of leading zeros in 5 bit numbers */
+ { 5, 4, 3, 3, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
+
+ /* Prepare bitmap */
+ memset(bitmap, 0, sizeof(bitmap));
+ if (frame->can_id & CAN_EFF_FLAG) {
+ /* bit 7 0 7 0 7 0 7 0
+ * bitmap[0-3] |.sBBBBBB BBBBBSIE EEEEEEEE EEEEEEEE| s = SOF, B = Base ID (11 bits), S = SRR, I = IDE, E = Extended ID (18 bits)
+ * bitmap[4-7] |ER10DLC4 00000000 11111111 22222222| R = RTR, 0 = r0, 1 = r1, DLC4 = DLC, Data bytes
+ * bitmap[8-11] |33333333 44444444 55555555 66666666| Data bytes
+ * bitmap[12-15] |77777777 ........ ........ ........| Data bytes
+ */
+ bitmap[0] = (frame->can_id & CAN_EFF_MASK) >> 23;
+ bitmap[1] = ((frame->can_id >> 18) & 0x3f) << 3 |
+ 3 << 1 | /* SRR, IDE */
+ ((frame->can_id >> 17) & 0x01);
+ bitmap[2] = (frame->can_id >> 9) & 0xff;
+ bitmap[3] = (frame->can_id >> 1) & 0xff;
+ bitmap[4] = (frame->can_id & 0x1) << 7 |
+ (!!(frame->can_id & CAN_RTR_FLAG)) << 6 |
+ 0 << 4 | /* r1, r0 */
+ (frame->can_dlc & 0xf);
+ memcpy(&bitmap[5], &frame->data, frame->can_dlc);
+ start = 1;
+ end = 40 + 8*frame->can_dlc;
+ } else {
+ /* bit 7 0 7 0 7 0 7 0
+ * bitmap[0-3] |.....sII IIIIIIII IRE0DLC4 00000000| s = SOF, I = ID (11 bits), R = RTR, E = IDE, DLC4 = DLC
+ * bitmap[4-7] |11111111 22222222 33333333 44444444| Data bytes
+ * bitmap[8-11] |55555555 66666666 77777777 ........| Data bytes
+ */
+ bitmap[0] = (frame->can_id & CAN_SFF_MASK) >> 9;
+ bitmap[1] = (frame->can_id >> 1) & 0xff;
+ bitmap[2] = ((frame->can_id << 7) & 0xff) |
+ (!!(frame->can_id & CAN_RTR_FLAG)) << 6 |
+ 0 << 4 | /* IDE, r0 */
+ (frame->can_dlc & 0xf);
+ memcpy(&bitmap[3], &frame->data, frame->can_dlc);
+ start = 5;
+ end = 24 + 8 * frame->can_dlc;
+ }
+
+ /* Calc and append CRC */
+ crc = calc_bitmap_crc(bitmap, start, end);
+ crc_be = htons(crc << 1);
+ assert(end % 8 == 0);
+ memcpy(bitmap + end / 8, &crc_be, 2);
+ end += 15;
+
+ /* Count stuffed bits */
+ mask = 0x1f;
+ lookfor = 0;
+ i = start;
+ stuffed = 0;
+ while (i < end) {
+ unsigned change;
+ unsigned bits = (bitmap[i / 8] << 8 | bitmap[i / 8 + 1]) >> (16 - 5 - i % 8);
+ lookfor = lookfor ? 0 : mask; /* We alternate between looking for a series of zeros or ones */
+ change = (bits & mask) ^ lookfor; /* 1 indicates a change */
+ if (change) { /* No bit was stuffed here */
+ i += clz[change];
+ mask = 0x1f; /* Next look for 5 same bits */
+ } else {
+ i += (mask == 0x1f) ? 5 : 4;
+ if (i <= end) {
+ stuffed++;
+ mask = 0x1e; /* Next look for 4 bits (5th bit is the stuffed one) */
+ }
+ }
+ }
+ return end - start + stuffed +
+ 3 + /* CRC del, ACK, ACK del */
+ 7 + /* EOF */
+ 3; /* IFS */
+}
+
+
+unsigned can_frame_length(struct canfd_frame *frame, enum cfl_mode mode, int mtu)
+{
+ int eff = (frame->can_id & CAN_EFF_FLAG);
+
+ if (mtu != CAN_MTU)
+ return 0; /* CANFD is not supported yet */
+
+ switch (mode) {
+ case CFL_NO_BITSTUFFING:
+ return (eff ? 67 : 47) + frame->len * 8;
+ case CFL_WORSTCASE:
+ return ((eff ? 389 : 269) + frame->len * 48) / 5;
+ case CFL_EXACT:
+ return cfl_exact((struct can_frame*)frame);
+ }
+ return 0; /* Unknown mode */
+}
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