common/spi_slave_common.c

   1 // included by spi_slave_{spi,usi}.c
   2
   3 uint8_t
   4 spi_slave_put(uint8_t *b, uint8_t n)
   5 {
   6   uint8_t i;
   7
   8   i = 0;
   9
  10   cli();
  11
  12   while ((i < n) && (tx.len + i < NUM_BUFFER_BYTES)) {
  13      uint8_t pos = tx.cur+tx.len+i;
  14      while (pos >= NUM_BUFFER_BYTES) {
  15           pos -= NUM_BUFFER_BYTES;
  16      }
  17      tx.buf[pos] = b[i];
  18      i++;
  19   }
  20
  21   tx.len += i;
  22
  23   sei();
  24
  25   // Return number of bytes added to tx buffer.
  26   return i;
  27 }
  28
  29 uint8_t
  30 spi_slave_get(uint8_t *b, uint8_t n)
  31 {
  32   uint8_t i;
  33
  34   i = 0;
  35
  36   cli();
  37
  38   while (rx.len && i < n)
  39   {
  40     uint8_t cur;
  41     b[i] = rx.buf[rx.cur];
  42     //rx.cur = (rx.cur + 1) % NUM_BUFFER_BYTES;
  43     cur = (rx.cur + 1);
  44     while (cur >= NUM_BUFFER_BYTES) {
  45           cur -= NUM_BUFFER_BYTES;
  46     }
  47     rx.cur = cur;
  48     --rx.len;
  49     ++i;
  50   }
  51
  52   sei();
  53
  54   return i;
  55 }