fw/eth.c (c906a48) - mips_sys · BlinkenArea

eth.c

#include "eth.h"

static volatile unsigned int *const eth_ptr =
  (volatile unsigned int *)0x80000400;

static unsigned int eth_idx_hw;
static unsigned int eth_rx_buf[2][256];
static unsigned int *eth_rx_pos;

/**
 * @brief provide new receive buffer
 * @param[in] ptr pointer to new receive buffer
 * @param[in] sz size of new receive buffer
 */
static void eth_rx_new_buf(void *ptr, unsigned int sz)
{
  eth_ptr[4] = (unsigned int)ptr; /* new start */
  eth_ptr[5] = (unsigned int)ptr + sz; /* new end */
  eth_ptr[6] = 1; /* set flag */
  while (eth_ptr[6] == 1); /* wait until processed */
}

/**
 * @brief get buffer position of ethernet receiver
 * @return current buffer position of ethernet receiver
 *
 * eveything before this position can be read
 */
static void * eth_rx_get_pos(void)
{
  return (void *)eth_ptr[0];
}

/** initialize receiver */
void eth_rx_init(void)
{
  // give buffer 0 to HW
  eth_idx_hw = 0;
  eth_rx_new_buf(eth_rx_buf[0], sizeof(eth_rx_buf[0]));
  // buffer 1 owned by SW is empty
  eth_rx_buf[1][0] = 0;
  eth_rx_pos = eth_rx_buf[1];
}

/**
 * @brief get next received packet
 * @param[out] *pptr pointer to packet data
 * @param[out] *psz size of packet
 * @return if a packet was received
 */
int eth_rx(void **pptr, unsigned int *psz)
{
  // current SW buffer is empty and HW buffer contains a packet
  if (*eth_rx_pos == 0 && eth_rx_get_pos() != eth_rx_buf[eth_idx_hw]) {
    // swap buffers
    eth_idx_hw = 1 - eth_idx_hw;
    // give new HW buffer to HW
    eth_rx_new_buf(eth_rx_buf[eth_idx_hw], sizeof(eth_rx_buf[eth_idx_hw]));
    // start reading packet data at begin of new SW buffer
    eth_rx_pos = eth_rx_buf[1 - eth_idx_hw];
  }

// SW buffer contains a packet
  if (*eth_rx_pos > 0) {
    // return size and pointer, advance position
    *psz = *eth_rx_pos;
    eth_rx_pos++;
    *pptr = eth_rx_pos;
    eth_rx_pos += *psz >> 2;
    return 1;
  }

// no packet received
  return 0;
}

mips_sys

implemented ethernet RX busmaster -> packet reception working