#include <stdio.h>  // using 'printf', 'scanf'
#include <stdlib.h> // using 'exit'
#include <string.h> // using 'strcmp'
#include <fcntl.h>	// using 'open'
#include <unistd.h> // using 'close'
#include <sys/mman.h> // using 'mmap', 'munmap'
#include <math.h>

#define FPGA_BASE_ADDRESS  0xc1a00000
#define FPGA_SLAVE_REG0OFF 0
#define FPGA_SLAVE_REG1OFF 12
#define FPGA_RESET_REG_OFF 64

#define MAP_SIZE 4096UL
#define MAP_MASK (MAP_SIZE-1)


char command[10];
int memfd;
void *mapped_base, *mapped_dev_base;
off_t dev_base = FPGA_BASE_ADDRESS;

void openFPGAInterface()
{
    memfd = open("/dev/mem", O_RDWR | O_SYNC);
    if( memfd == -1 )
    {
        printf("CL-Interface: Can't open /dev/mem.\n");
        exit(EXIT_FAILURE);
    }
    printf("CL-Interface: /dev/mem opened.\n");

    mapped_base = mmap(0, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, memfd, dev_base & ~MAP_MASK);
    if( mapped_base == (void *) -1 )
    {
        printf("CL-Interface: Can't map the memory to user space.\n");
        exit(EXIT_FAILURE);
    }
    printf("CL-Interface: Memory mapped at address %p.\n", mapped_base);

    mapped_dev_base = mapped_base + (dev_base & MAP_MASK);
}

void CostasLoopProcessing()
{
    unsigned long samples[512];
    unsigned long val;

    // push 512 samples to the FPGA
    unsigned int i;
    for (i = 0; i < 512; i++)
    {
        *((unsigned long *) (mapped_dev_base + FPGA_SLAVE_REG1OFF)) = 0x00000000;
    }

    // wait for the system to finish processing
    // (stop if 50000 reads and FPGA circuit still not ready)
    unsigned int j = 0;
    unsigned int stop = 0;
    while(j < 5000 && stop == 0)
    {
        val = *((unsigned long *) (mapped_dev_base + FPGA_SLAVE_REG0OFF));

        // exit case to start reading
        if (val != 0xDEADDEAD)
        {
            printf("CL-Interface: Caught exit sequence on the bus, stopping poll loop\n");
            printf("CL-Interface: Waited for %d cycles\n", j);
            samples[0] = val;
            stop = 1; // stop waiting for FPGA circuit, start reading
        }
        j++;
    }

    if (stop == 0)
    {
        printf("CL-Interface: Never received ready flag\n");
    }
    else
    {
        printf("CL-Interface: Reading back 512 samples\n");

         // read back 512 samples
         unsigned int k;
         for (k = 1; k < 512; k++)
         {
             val = *((unsigned long *) (mapped_dev_base + FPGA_SLAVE_REG0OFF));
             samples[k] = val;
         }
    }

    unsigned int p;
    for (p = 0; p < 512; p++)
    {
        printf("CL-Interface: Sample %d: #%x\n", p, samples[p]);
    }
}

void closeFPGAInterface()
{

    if( munmap(mapped_base, MAP_SIZE) == -1 )
    {
        printf("CL-Interface: Can't unmap memory from user space.\n");
        exit(EXIT_FAILURE);
    }

    close(memfd);
}