/*
 * Ymodem send routine.  Only supports 1K blocks and CRC mode.
 */

#include <string.h>
#include <stdio.h>
#include "ymsend.h"

enum {
  SOH = 0x01,
  STX = 0x02,
  EOT = 0x04,
  ACK = 0x06,
  NAK = 0x15,
  CAN = 0x18,
};

/*
 * Append a CRC16 to a block
 */
static void add_crc16(uint8_t *blk, int len)
{
  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
  };
  uint16_t crc = 0;

  while (len--)
    crc = crctab[(crc >> 8) ^ *blk++] ^ crc << 8;

  *blk++ = crc >> 8;
  *blk = crc;
}

static void send_ack_blk(struct serial_if *sif, const void *data, size_t bytes)
{
  uint8_t ack_buf;

  if (bytes)
    sif->write(sif, data, bytes);

  do {
    do {
      sif->read(sif, &ack_buf, 1);
    } while (ack_buf != ACK && ack_buf != NAK);
  } while (ack_buf == NAK);
}

static const uint8_t eot_buf = EOT;

void send_ymodem(struct serial_if *sif,  struct file_info *fileinfo,
		 void (*gen_data)(void *, size_t, struct file_info *, size_t))
{
  uint8_t ack_buf, blk_buf[1024+5], *np, *q;
  const char *p;
  size_t len, lx, pos;
  int blk;

  /* Wait for initial handshake */
  printf("Waiting for handshake...\n");
  do {
    sif->read(sif, &ack_buf, 1);
  } while (ack_buf != 'C');

  /* Send initial batch header (filename, length etc.) */
  q = blk_buf + 3;
  p = fileinfo->name;
  while (*p)
    *q++ = *p++;
  *q++ = '\0';

  lx = len = fileinfo->size;
  do {
    q++;
    lx /= 10;
  } while (lx);

  np = q;
  lx = len;
  do {
    *--np = (lx % 10) + '0';
    lx /= 10;
  } while (lx);

  while (q < blk_buf+1024+3)
    *q++ = 0;

  blk = 0;
  pos = 0;
  do {
    if (blk != 0) {
      gen_data(blk_buf+3, 1024, fileinfo, pos);
      pos += 1024;
      len = (len < 1024) ? 0 : len-1024;
    }

    blk_buf[0] = STX;
    blk_buf[1] = blk;
    blk_buf[2] = ~blk;
    add_crc16(blk_buf+3, 1024);

    printf("Sending block %d...\r", blk);
    send_ack_blk(sif, blk_buf, 1024+5);

    blk++;
  } while(len);

  printf("\nSending EOT...\n");
  send_ack_blk(sif, &eot_buf, 1);
  printf("Done.\n");
}

void end_ymodem(struct serial_if *sif)
{
  uint8_t ack_buf;
  uint8_t blk_buf[128+5];

  /* Wait for initial handshake */
  printf("END: Waiting for handshake...\n");
  do {
    sif->read(sif, &ack_buf, 1);
  } while (ack_buf != 'C');

  memset(blk_buf, 0, sizeof blk_buf);
  blk_buf[0] = SOH;
  blk_buf[1] = 0;
  blk_buf[2] = 0xff;
  add_crc16(blk_buf+3, 128);
  printf("Sending block 0...\n");
  send_ack_blk(sif, &blk_buf, 128+5);

  printf("Sending EOT...\n");
  sif->write(sif, &eot_buf, 1);
  /* rb doesn't ack the EOT for an end batch transfer. */
  printf("Done.\n");
}
