加速器本地内存中的DMA传输

对于加速器内部的本地内存进行DMA传输，需要使用相关的编程接口。以下代码示例演示了在FPGA加速器内部进行DMA传输的方法。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "sys/alt_dma.h"
#include "sys/alt_irq.h"
#include "sys/alt_types.h"
#include "altera_avalon_dma_regs.h"

void dma_isr(void *context) {
    volatile int *status_reg = (volatile int *)(DMA_0_BASE + ALT_DMA_STATUS_REG_OFS);
    *status_reg = 0;
}

int main(void) {

    alt_dma_txchan txchan;
    alt_dma_rxchan rxchan;
    alt_u32 *rx_buffer = NULL;
    alt_u32 *tx_buffer = NULL;
    int count = 0;

    // Initialize the DMA controller
    if (alt_dma_init() < 0) {
        printf("Error: Could not initialize the DMA controller\n");
        return -EIO;
    }

    // Allocate buffers for DMA transfer
    rx_buffer = (alt_u32 *)malloc(DMA_BUF_LEN);
    tx_buffer = (alt_u32 *)malloc(DMA_BUF_LEN);

    if (rx_buffer == NULL || tx_buffer == NULL) {
        printf("Error: Could not allocate buffer for DMA transfer\n");
        return -ENOMEM;
    }

    // Initialize the data to be transferred
    for (count = 0; count < DMA_BUF_LEN/4; count++) {
        tx_buffer[count] = count;
        rx_buffer[count] = 0;
    }

    // Open the DMA channels
    txchan = alt_dma_txchan_open(DMA_DEVICE_NAME);
    rxchan = alt_dma_rxchan_open(DMA_DEVICE_NAME);

    // Set up the DMA transfer
    alt_dma_txchan_send(txchan, tx_buffer, DMA_BUF_LEN, NULL, NULL); // Write data to accelerator
    alt_dma_rxchan_prepare(rxchan, rx_buffer, DMA_BUF_LEN, dma_isr, NULL); // Read result from accelerator

    // Wait for the DMA transfer to complete
    alt_dma_txchan_wait(txchan);
    alt_dma_rxchan_wait(rxchan);

    //