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packet.c
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packet.c
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/* packet.c - an elf and spin binary loader for the Parallax Propeller microcontroller
Copyright (c) 2011 David Michael Betz
See license at the end of the file
*/
#include <stdio.h>
#include <string.h>
#include "packet.h"
#include "osint.h"
/* packet format: SOH pkt# type length-lo length-hi hdrchk length*data crc1 crc2 */
#define HDR_SOH 0
#define HDR_TYPE 1
#define HDR_LEN_HI 2
#define HDR_LEN_LO 3
#define HDR_CHK 4
/* packet header and crc lengths */
#define PKTHDRLEN 5
#define PKTCRCLEN 2
/* maximum length of a frame */
#define FRAMELEN (PKTHDRLEN + PKTMAXLEN + PKTCRCLEN)
/* protocol characters */
#define SOH 0x01 /* start of a packet */
#define updcrc(crc, ch) (crctab[((crc) >> 8) & 0xff] ^ ((crc) << 8) ^ (ch))
static const uint16_t crctab[256] = {
0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,
0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,
0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4,
0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,
0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,
0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12,
0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41,
0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,
0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,
0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,
0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,
0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,
0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,
0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,
0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3,
0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92,
0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,
0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,
0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0
};
int SendPacket(int type, uint8_t *buf, int len)
{
uint8_t hdr[PKTHDRLEN], crc[PKTCRCLEN], *p;
uint16_t crc16 = 0;
int cnt;
/* setup the frame header */
hdr[HDR_SOH] = SOH; /* SOH */
hdr[HDR_TYPE] = type; /* type type */
hdr[HDR_LEN_HI] = (uint8_t)(len >> 8); /* data length - high byte */
hdr[HDR_LEN_LO] = (uint8_t)len; /* data length - low byte */
hdr[HDR_CHK] = hdr[1] + hdr[2] + hdr[3]; /* header checksum */
printf("tx length %d\n", len);
printf("%02x %02x %02x\n", hdr[1], hdr[2], hdr[3]);
/* compute the crc */
for (p = buf, cnt = len; --cnt >= 0; ++p)
crc16 = updcrc(crc16, *p);
crc16 = updcrc(crc16, '\0');
crc16 = updcrc(crc16, '\0');
/* add the crc to the frame */
crc[0] = (uint8_t)(crc16 >> 8);
crc[1] = (uint8_t)crc16;
/* send the packet */
tx(hdr, PKTHDRLEN);
if (len > 0)
tx(buf, len);
tx(crc, PKTCRCLEN);
return 0;
}
int ReceivePacket(int *pType, uint8_t *buf, int len)
{
uint8_t hdr[PKTHDRLEN], crc[PKTCRCLEN];
int actual_len, chk;
uint16_t crc16 = 0;
int retries = 10;
printf("Looking for SOH\n");
/* look for start of packet */
do {
rx_timeout(&hdr[HDR_SOH], 1, 100);
} while (hdr[HDR_SOH] != SOH && --retries >= 0);
printf(" retries %d\n", retries);
/* check for a timeout waiting for the packet */
if (retries < 0)
return -1;
/* receive the rest of the header */
rx(&hdr[HDR_TYPE], PKTHDRLEN - 1);
printf("%02x %02x %02x %02x %02x\n", hdr[0], hdr[1], hdr[2], hdr[3], hdr[4]);
/* check the header checksum */
chk = (hdr[1] + hdr[2] + hdr[3]) & 0xff;
if (hdr[HDR_CHK] != chk)
return -1;
printf("checksum okay\n");
/* make sure the buffer is big enough for the payload */
actual_len = (hdr[HDR_LEN_HI] << 8) | hdr[HDR_LEN_LO];
printf("rx length %d\n", actual_len);
if (actual_len > len)
return -1;
printf("length okay\n");
/* receive the packet payload */
rx(buf, actual_len);
/* compute the crc */
for (len = actual_len; --len >= 0; )
crc16 = updcrc(crc16, *buf++);
/* receive the crc */
rx(crc, PKTCRCLEN);
/* check the crc */
crc16 = updcrc(crc16, crc[0]);
crc16 = updcrc(crc16, crc[1]);
if (crc16 != 0)
return -1;
printf("crc okay\n");
/* return packet type and the length of the payload */
*pType = hdr[HDR_TYPE];
return actual_len;
}
/*
Permission is hereby granted, free of charge, to any person obtaining a copy of this software
and associated documentation files (the "Software"), to deal in the Software without restriction,
including without limitation the rights to use, copy, modify, merge, publish, distribute,
sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or
substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/