Nios® V Processor Software Developer Handbook

ID 743810
Date 2/14/2023
Public

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Document Table of Contents

6.9.2.1. Memory-to-Memory DMA Transactions

#include <stdio.h>

#include <stdlib.h>

#include "sys/alt_dma.h"

#include "system.h"

static volatile int rx_done = 0;
/*
 * Callback function that obtains notification that the data
 * is received.*/
static void done(void * handle, void * data) {
  rx_done++;
}
int main(int argc, char * argv[], char * envp[]) {
  int rc;
  alt_dma_txchan txchan;
  alt_dma_rxchan rxchan;
  void * tx_data = (void * ) 0x901000; /* pointer to data to send */
  void * rx_buffer = (void * ) 0x902000; /* pointer to rx buffer */
  /* Create the transmit channel */
  if ((txchan = alt_dma_txchan_open("/dev/dma_0")) == NULL) {
    printf("Failed to open transmit channel\n");
    exit(1);
  }
  /* Create the receive channel */
  if ((rxchan = alt_dma_rxchan_open("/dev/dma_0")) == NULL) {
    printf("Failed to open receive channel\n");
    exit(1);
  }

  /* Post the transmit request */
  if ((rc = alt_dma_txchan_send(txchan,
      tx_data,
      128,
      NULL,
      Null)) < 0) {
    printf("Failed to post transmit request, reason = %i\n", rc);
    exit(1);
  }
  /* Post the receive request */
  if ((rc = alt_dma_rxchan_prepare(rxchan,
        rx_buffer,
        128,
        done,
        NULL
      }
    } < 0) {
    printf("Failed to post read request, reason = %i\n", rc);
    exit(1);
  }
  /* wait for transfer to complete */
  while (!rx_done);
  printf("Transfer successful!\n");
  return 0;
}