source: soft/giet_vm/applications/mjpeg/tg.c @ 723

/////////////////////////////////////////////////////////////////////////////////////////
// File   : tg.c   
// Date   : octobre 2015
// author : Alain Greiner
/////////////////////////////////////////////////////////////////////////////////////////
// This file define the code of the TG (trafic generator) thread for MJPEG application.
// It transfer the byte stream from the file identified by the fd argument to a 1024 
// bytes local buffer. It analyses the byte stream to detect the End_of_Image markers.
// All the bytes corresponding to a single image (from the first byte, to the EOI marker
// included) is written in the TG_2_DEMUX[index] channel of a single cluster, 
// in increasing order in of the cluster index.
/////////////////////////////////////////////////////////////////////////////////////////

#include <stdio.h>
#include <mwmr_channel.h>
#include <stdint.h>
#include "mjpeg.h"

// macro to use a shared TTY
#define PRINTF(...)    lock_acquire( &tty_lock ); \
                       giet_tty_printf(__VA_ARGS__);  \
                       lock_release( &tty_lock );

//////////////////////////////////////
__attribute__ ((constructor)) void tg()
///////////////////////////////////////
{ 
    // get platform parameters
    uint32_t  x_size;
    uint32_t  y_size;
    uint32_t  nprocs;
    giet_procs_number( &x_size , &y_size , &nprocs );

    // get processor coordinates
    uint32_t x , y , p;
    giet_proc_xyp( &x , &y , &p );

    // private TTY allocation
    //  giet_tty_alloc( 0 );

    PRINTF("\n[MJPEG] thread TG starts on P[%d,%d,%d]\n", x , y , p )

   // allocate input buffer : 1024 bytes
    uint8_t        bufin[1024];

    // allocate output bufio to access MWMR channel : 64 bytes == 16 words
    mwmr_bufio_t  bufio;
    uint8_t       bufout[64]; 
    mwmr_bufio_init( &bufio , bufout , 64 , 0 , tg_2_demux[0] );

    uint32_t  image;           // image index
    uint32_t  cluster;         // cluster index / modulo x_size*y_size
    uint32_t  ptr;             // byte pointer in input buffer
    uint32_t  eoi_found;       // boolean : End-of-Image found
    uint32_t  ff_found;        // boolean : 0xFF value found
    uint32_t  bytes_count;     // mumber of bytes in compressed image
       
    // initialise image and cluster index, and bufin pointer
    image   = 0;
    cluster = 0;
    ptr     = 0;

    while( image < MAX_IMAGES )  // one compressed image per iteration
    {
        // initialise image specific variables
        eoi_found   = 0;
        ff_found    = 0;
        bytes_count = 0; 
       
        // re-initialise the destination buffer for each image
        bufio.mwmr = tg_2_demux[cluster];

        // scan bit stream until EOI found
        // transfer one byte per iteration from input buffer to output bufio
        while ( eoi_found == 0 )
        {
            // - tranfer 1024 bytes from file to input buffer when input buffer empty.
            // - return to first byte in input file when EOF found, 
            //   to emulate an infinite stream of images.
            if ( ptr == 0 )
            {
                uint32_t r = giet_fat_read( fd , bufin , 1024 );
                if ( r < 1024 ) 
                {
                    giet_fat_lseek( fd , 0 , SEEK_SET );
                    giet_fat_read( fd , bufin + r , 1024 - r );
                }
            }

            // transfer one byte from input buffer to output bufio
            mwmr_bufio_write_byte( &bufio , bufin[ptr] );

            // analyse this byte to find EOI marker OxFFD8
            // flush the output buffer when EOI found
            if ( ff_found )  // possible End of Image
            { 
                ff_found = 0;
                if ( bufin[ptr] == 0xD9 )   // End of Image found
                {
                    // exit current image
                    eoi_found = 1;

                    // flush output bufio
                    mwmr_bufio_flush( &bufio );
                }
            }
            else           // test if first byte of a marker
            {
                if ( bufin[ptr] == 0xFF )  ff_found = 1;
            }        

            // increment input buffer pointer modulo 1024
            ptr++;
            if ( ptr == 1024 ) ptr = 0;
                
            // increment bytes_count for current image
            bytes_count++;

        } // end while (eoi)
 
#if DEBUG_TG
PRINTF("\nTG send image %d to cluster %d at cycle %d : %d bytes\n",
       image , cluster , giet_proctime() , bytes_count )
#endif
        // increment image index
        image++;

        // increment cluster index modulo (x_size*y_size)   
        cluster++; 
        if (cluster == x_size * y_size) cluster = 0;    

    } // end while on images

    giet_pthread_exit("TG completed");

}  // end tg()