crcdma.c

采用nios2的嵌入式数字钟的设计与实现

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <io.h>
#include "system.h"
#include "altera_avalon_pio_regs.h"
#include "altera_avalon_dma.h"
#include "alt_types.h"
#include <time.h>
#include <unistd.h>
#include <sys/alt_timestamp.h>
#include "sys/alt_dma.h"
#include "altera_avalon_dma_regs.h"
#include "alt_types.h"

// Global Variable to count hex digits:
alt_u32 hex_digits;

alt_dma_txchan tx;

volatile int dma_complete = 0;

/**********************************************************************
 *
 * Function:    sevenseg_set_hex()
 *
 * Description: Decode hex number to format for 7-seg display.
 *              Also: sends data to the 7-seg display PIO
 *
 * Notes:       
 *
 * Returns:     The 7-seg-decoded values of a hex digit input.
 *
 **********************************************************************/
 static void sevenseg_set_hex(int hex)
 {
   static alt_u8 segments[16] = {
     0x81, 0xCF, 0x92, 0x86, 0xCC, 0xA4, 0xA0, 0x8F, 0x80, 0x84, /* 0-9 */
     0x88, 0xE0, 0xF2, 0xC2, 0xB0, 0xB8 };                       /* a-f */

   unsigned int data = segments[hex & 15] | (segments[(hex >> 4) & 15] << 8);

   IOWR_ALTERA_AVALON_PIO_DATA(SEVEN_SEG_PIO_BASE, data);
 }

void dma_done (void* handle){
  dma_complete = 1;
}

/**********************************************************************
 *
 * Function:    crcCompute()
 *
 * Description: Compute the CRC checksum of a binary message block.
 *
 * Notes:       This function expects that crcInit() has been called
 *              first to initialize the CRC lookup table.
 *
 * Returns:     The CRC of the data.
 *
 **********************************************************************/

volatile alt_u16 crcCompute(unsigned long *data_block, unsigned int nWords, int hex)
{
  alt_u16 word;

  IOWR(CRC_PERIPH_BASE,0,0x0000FFFF);

    alt_dma_txchan_ioctl(tx, 
      ALT_DMA_RX_STREAM_ON, 
      (void*)(CRC_PERIPH_BASE + 0x4));
      
    alt_avalon_dma_send (tx, 
                 data_block,
                 nWords  ,
                 //dma_done, 
                 NULL,
                 NULL);
                 
  while (IORD_ALTERA_AVALON_DMA_STATUS (AVALON_DMA_BASE) & 
   ALTERA_AVALON_DMA_STATUS_BUSY_MSK);  
     
    word = (IORD(CRC_PERIPH_BASE,1));
    return (word);

}   /* crcCompute() */

int main(void)
{
  
    #define data_block_begin 0x600000
    #define data_block_end   0x63ffff
    #define data_sram_copy   0x8a0000
 
    alt_u16 crc_result;
    unsigned int hex_digits;
    unsigned int* read_data;
    unsigned int* write_data;

    alt_u32 data_block_length;
    
    alt_u32 num_ticks = 0;
    alt_u32 time1, time2, timer_overhead;
    
    data_block_length = (char*)data_block_end - (char*)data_block_begin + 1;

    tx = alt_dma_txchan_open ("/dev/avalon_dma");
      
    // Copy data block to SRAM so that Flash access time does not effect results
    write_data = (int*)data_sram_copy;
    for (read_data = (int*)data_block_begin; (int*)read_data <= (int*)data_block_end; read_data++)
    {
      *write_data = *read_data;
      write_data++;
     }
  
     // Start Timer:    
     if(alt_timestamp_start() < 0)
     {
      printf("Timer init failed \n");
      exit(0);
     }

     // Get the number of clocks it takes + record time stamp:
   	 time1 = alt_timestamp();
     time2 = alt_timestamp();
     timer_overhead = time2 - time1;

   	 time1 = alt_timestamp();

    	for (hex_digits = 0; hex_digits <= 0x80; hex_digits++)
    	{
     	   crc_result = crcCompute((long*)data_sram_copy,data_block_length,hex_digits);
           
     	    sevenseg_set_hex(hex_digits);
  	}

   	time2 = alt_timestamp();
    	num_ticks = time2 - time1 - timer_overhead;
       
   	printf ("\nCRC for Data Block = 0x%x.\n", crc_result);
    printf("CPU time(ms): %.*f\n", 2, ((float)num_ticks/(float)alt_timestamp_freq()) * (float)1000); 

}