fft code in c for PIC16f877

#include <16F877A.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=20000000)
#use rs232(baud=115200, xmit=PIN_C6, rcv=PIN_C7)  // Jumpers: 8 to 11, 7 to 12
#include <MATH.h>
#include "header.h"
#include "tables.c"

void main() {
   signed int zeroimag = 0;
   long int SRAMpos = 0;
   long int i, l2, l,l1, j;
   char tempchar;
   signed int real, imag, real1, imag1;
   signed int tempval;
   long int i1,  t1, t2, u;
   long z, h, tempr, tempi;
   
   //signed int i, i1, j, l, l1, l2, t1, t2, u;

   setup_port_a( AN0 );
   setup_adc( ADC_CLOCK_INTERNAL );
   set_adc_channel( 0 );


   do {
      printf(" \n\r press a to take analog sample \n\r");
      do {
         tempchar = getc();
      } while (tempchar != 'a');


      for (i=0; i<256; i++) {
         setSRAMaddy(SRAMpos, 0);
         real = Read_ADC();
         real = (real-128)/4;
         writeSRAM(real);
         //printf("\n\r---> %d \n\r", real);
         setSRAMaddy(SRAMpos, 1);
         writeSRAM(zeroimag);
         delay_us(2194);
         SRAMpos++;
         printf("%d  ", real);
      }

      l2 = 128;
   	i=0;
   	for(l=0;l<255;l++) {
   		if(l < i) {
            setSRAMaddy(l, 0);
            j = readSRAM();
            
            setSRAMaddy(i, 0);
            real1 = readSRAM();
            
            setSRAMaddy(l, 0);
            writeSRAM(real1);
            
            setSRAMaddy(i, 0);
            writeSRAM(j);
           
   		}
   		l1 = l2;
   		while (l1 <= i){
   			i -= l1;
   			l1 >>= 1;
   		}
   		i += l1;
   	}

   	/* Compute the FFT */
   	u = 0;
   	l2 = 1;
   	for(l=0;l<8;l++){
   		l1 = l2;
   		l2 <<= 1;
   		for(j=0;j<l1;j++){
   			for(i=j;i<256;i+=l2){
   				i1 = i + l1;

               setSRAMaddy(i, 0);
               real = readSRAM();

               setSRAMaddy(i, 1);
               imag = readSRAM();

               setSRAMaddy(i1, 0);
               real1 = readSRAM();

               setSRAMaddy(i1, 1);
               imag1 = readSRAM();

   				t1 = (u1[u]*real1 - u2[u]*imag1)/32;
   				t2 = (u1[u]*imag1 + u2[u]*real1)/32;

               
               setSRAMaddy(i1, 0);
               writeSRAM((real-t1));
               
               setSRAMaddy(i1, 1);
               writeSRAM((imag-t2));

               setSRAMaddy(i, 0);
               writeSRAM((real+t1));
               
               setSRAMaddy(i, 1);
               writeSRAM((imag+t2));

   			}
   			u++;
   		}
   	}


      for (i=124; i<133; i++){
         setSRAMaddy((int8)i, 0);
         real = readSRAM();
         setSRAMaddy((int8)i, 1);
         imag = readSRAM();
         //printf("\n\r Value %ld: %d + i%d\n\r", i, real, imag);
      }


   	/* Find the highest amplitude value */
   	/* start at index 1 because 0 can hold high values */
   	j=1;
   	l=0;
   	for ( i=1; i<128; i++ ) {
         setSRAMaddy(i, 0);
         real = readSRAM();

         tempr = abs(real*real);

         setSRAMaddy(i, 1);
         imag = readSRAM();
         tempi = abs(imag*imag);



         l1 = tempr + tempi;
       
   		if (l1 > l) {
   			j = i;
   			l = l1;
   		}
   	}

      setSRAMaddy(j, 0);
      real = readSRAM();

      setSRAMaddy(j, 1);
      imag = readSRAM();

      tempi = 1.5625*j;

      printf("\n\r---> position %ld: %d + i %d value: %ld freq: %ld \n\r", j, real, imag, l1,tempi);

      u = 0;
      l = 0;
      l2 = 0;
      l1 = 0;
      j = 0;
      i1 = 0;
      SRAMpos = 0;
      t1 = 0;
      t2 = 0;
      real = 0;
      imag = 0;
      real1 = 0;
      imag1 = 0;
   } while (TRUE);
}


signed int readSRAM(void) {
   char temp_char = 0;
   int i;

   // Delay after seeing that data is available so that the
   // data can be written to the SRAM.
   //delay_us(4);

   // Set the SRAM enables to READ.
   //OE = 0;
   //WE = 1;
   //CS = 0;
   output_low(OE_PIN);
   output_high(WE_PIN);
   //output_low(CS_PIN);

   delay_us(1);

   // Reads from the SRAM
   temp_char = input_d();

   delay_us(1);

   // Stop READing by setting to IDLE state
   //OE = 1;
   //WE = 1;
   //CS = 0;
   output_high(OE_PIN);
   output_high(WE_PIN);
   //output_low(CS_PIN);

   return temp_char;
}



/***************************************************
* writeSRAM()                                      *
*                                                  *
*    Sets the correct enables and clocks the       *
*    counter to write to SRAM                      *
***************************************************/
void writeSRAM(signed int value) {
   int i;
   // Set SRAM to WRITE
   //chartobin(value);

   output_high(OE_PIN);          // Enables WRITE
   output_low(WE_PIN);
   //output_low(CS_PIN);
   delay_us(1);
   //OE = 1;
   //WE = 0;
   //CS = 0;

   output_d(value);

   delay_us(1);

   // Stop WRITING by setting to IDLE state
   //OE = 1;
   //WE = 1;
   //CS = 1;
   output_high(OE_PIN);
   output_high(WE_PIN);
   //output_high(CS_PIN);
   delay_us(1);

   // Clear I/O pins

   input_d();
   delay_us(1);
}


void setSRAMaddy (unsigned int pos, short img) {
   output_b(pos);
   if (img) { output_high(PIN_C3); }
   else { output_low(PIN_C3); }
   delay_us(1);
}