100 lines
1.8 KiB
C
100 lines
1.8 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <string.h>
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#include <stdint.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include "context.h"
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#include "filedata.h"
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#include "logging.h"
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enum {
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XM_SOH = 0x01,
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XM_EOT = 0x04,
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XM_ACK = 0x06,
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XM_NACK = 0x15,
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XM_C = 0x43
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};
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struct xmodem_pkt {
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uint8_t header;
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uint8_t count;
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uint8_t ncount;
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uint8_t data[128];
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uint16_t crc;
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} __attribute__((packed));
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static void calc_crc(struct xmodem_pkt *pkt)
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{
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uint16_t crc = 0;
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uint8_t *ptr = pkt->data;
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int i, j;
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for (i = 0; i < sizeof(pkt->data); i++) {
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crc = crc ^ (*ptr++ << 8);
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for (j = 0; j < 8; j++)
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crc = (crc & 0x8000) ? (crc << 1 ^ 0x1021) : (crc << 1);
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}
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/* byteswap */
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pkt->crc = ((crc & 0xFF00) >> 8) | ((crc & 0xFF) << 8);
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}
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int xmodem_read(int fd, void *privdata)
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{
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struct context *ctx = (struct context *)privdata;
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struct xmodem_pkt pkt;
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int len = read(fd, &pkt, sizeof(pkt));
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if (len <= 0) {
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log_print(LOG_WARN, "xmodem_read(): read()");
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return -1;
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}
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int pktnum = 0;
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switch (pkt.header) {
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case XM_C: /* first packet */
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log_print(LOG_DEBUG, "%s: XMODEM started", ctx->devname);
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pktnum = 0;
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break;
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case XM_ACK: /* next packet */
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if (ctx->lastpkt * 128 == ctx->file->size)
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return -1;
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pktnum = ctx->lastpkt +1;
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break;
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case XM_NACK: /* resend last packet */
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pktnum = ctx->lastpkt;
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break;
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}
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if (pktnum * 128 < ctx->file->size) {
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pkt.header = XM_SOH;
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pkt.count = ((pktnum +1) & 0xFF);
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pkt.ncount = 0xFF - pkt.count;
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memcpy(pkt.data, (void *)(ctx->file->data) + pktnum * 128, 128);
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calc_crc(&pkt);
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write(fd, &pkt, sizeof(pkt));
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} else {
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log_print(LOG_DEBUG, "%s: XMODEM completed", ctx->devname);
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pkt.header = XM_EOT;
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write(fd, &pkt, 1);
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}
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ctx->lastpkt = pktnum;
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return 0;
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}
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