#include "include/circular_buffer.h"
#include "include/wifi.h"
#include "include/spi_drv.h"

Byte __xdata circular_buffer[CBUF_SIZE];
Int16 cbuf_head;
Int16 cbuf_tail;

void cbuf_init() {
  cbuf_head=0;
  cbuf_tail=0;
}

Int16 cbuf_space() {
  if (cbuf_tail >= cbuf_head) {
    return CBUF_SIZE-cbuf_tail+cbuf_head-1;
  }
  else {
    return cbuf_head-cbuf_tail-1;
  }
}

void cbuf_fill_buffer() {
  Byte len_lo;
  Byte len_hi;
  Int16 len_recv = 0;
  Int16 i;
  Int16 buf_space = cbuf_space();

  if (!buf_space) return;

  wifi_select();
  Spi_write_data(WIFI_COMMAND_READ);
  Spi_wait_eot();
  Spi_write_dummy();
  Spi_wait_eot();
  len_hi=Spi_read_data();
  Spi_write_dummy();
  Spi_wait_eot();
  len_lo=Spi_read_data();

  len_recv=len_hi;
  len_recv = len_recv << 8;
  len_recv |= len_lo;
  if (len_recv > buf_space) {
    len_recv = buf_space;
  }

  for (i=0; i<len_recv; i++) {
    Spi_write_dummy();
    Spi_wait_eot();
    circular_buffer[cbuf_tail]=Spi_read_data();
    cbuf_tail=(cbuf_tail+1);
    if (cbuf_tail==CBUF_SIZE) cbuf_tail=0;
  }

  wifi_deselect();
}

void cbuf_fill_buffer_force() {
  while (!cbuf_full()) {
    cbuf_fill_buffer();
  }
}

Byte cbuf_push_element(Byte element_a) {
  if (cbuf_full()) {
    return 0;
  }
  circular_buffer[cbuf_tail]=element_a;
  cbuf_tail=(cbuf_tail+1);
  if (cbuf_tail==CBUF_SIZE) cbuf_tail=0;
  return 1;
}

/* doesn't check for underflow
 do it on your own
*/
Byte cbuf_pop_element() {
  Byte temp = circular_buffer[cbuf_head];
  ++cbuf_head;
  if (cbuf_head==CBUF_SIZE) cbuf_head=0;
  return temp;
}