#include <stdio.h>
#include <stdlib.h>

Include dependency graph for jacobi.c:

Macros
#define	SIZE 832

#define	T 64

Typedefs
typedef float	float_t

Functions
void	get_data (char filename[])

void	write_data (char filename[])

void	jacobi ()

int	main (int argc, char *argv[])

Variables
float_t	space [SIZE][SIZE]

float_t	save [SIZE][SIZE]

Macro Definition Documentation

◆ SIZE

#define SIZE 832

Definition at line 4 of file jacobi.c.

◆ T

#define T 64

Definition at line 5 of file jacobi.c.

Typedef Documentation

◆ float_t

typedef float float_t

Definition at line 3 of file jacobi.c.

Function Documentation

◆ get_data()

void get_data ( char filename[] )

Get *.pgm file type

Skip comment lines

Put back good char

Get image dimensions

Get grey levels

Get ONE carriage return

Definition at line 11 of file jacobi.c.

                                {
   int i, j, nx, ny;
   unsigned char c;
   FILE *fp;
  
   if ((fp = fopen(filename, "r")) == NULL) {
     perror("Error loading file");
     exit(1);
   }
  
   /* Get *.pgm file type */
   c = fgetc(fp);
   c = fgetc(fp);
  
   /* Skip comment lines */
   do {
     while((c = fgetc(fp)) != '\n');
   } while((c = fgetc(fp)) == '#');
  
   /* Put back good char */
   ungetc(c,fp);
  
   /* Get image dimensions */
   fscanf(fp, "%d %d\n", &nx, &ny);
   /* Get grey levels */
   fscanf(fp,"%d",&i);
   /* Get ONE carriage return */
   fgetc(fp);
   printf("Input image  : x=%d y=%d grey=%d\n", nx, ny, i);
  
  
   for(i = 0;i < SIZE; i++)
     for(j = 0;j < SIZE; j++) {
       c = fgetc(fp);
       space[i][j] = c;
     }
  
   fclose(fp);
 }

References exit, printf(), SIZE, and space.

Referenced by main().

Here is the call graph for this function:

Here is the caller graph for this function:

◆ jacobi()

void jacobi ( )

Use 2 array in flip-flop to have dataparallel forall semantics. I could use also a flip-flop dimension instead...

Definition at line 74 of file jacobi.c.

               {
   int i, j;
  
   /* Use 2 array in flip-flop to have dataparallel forall semantics. I
      could use also a flip-flop dimension instead... */
  kernel1:
   for(i = 1;i < SIZE - 1; i++)
     for(j = 1;j < SIZE - 1; j++) {
       save[i][j] = 0.25*(space[i - 1][j] + space[i + 1][j]
                           + space[i][j - 1] + space[i][j + 1]);
     }
   for(i = 1;i < SIZE - 1; i++)
     for(j = 1;j < SIZE - 1; j++) {
       space[i][j] = 0.25*(save[i - 1][j] + save[i + 1][j]
                           + save[i][j - 1] + save[i][j + 1]);
     }
 }

References save, SIZE, and space.

Referenced by main().

Here is the caller graph for this function:

◆ main()

int main	(	int	argc,
		char *	argv[]
	)

Definition at line 93 of file jacobi.c.

                                  {
   int t;
  
   if (argc != 2) {
     fprintf(stderr,
             "%s needs only one argument that is the PGM image input file\n",
             argv[0]);
     exit(1);
   }
   get_data(argv[1]);
  
   for(t = 0; t < T; t++)
     jacobi();
  
   write_data("output.pgm");
  
   return 0;
 }

References exit, fprintf(), get_data(), jacobi(), T, and write_data().

Here is the call graph for this function:

◆ write_data()

void write_data ( char filename[] )

Write the PGM header:

Definition at line 52 of file jacobi.c.

                                  {
   int i,j;
   unsigned char c;
   FILE *fp;
  
   if ((fp = fopen(filename, "w")) == NULL) {
     perror("Error opening file");
     exit(2);
   }
  
   /* Write the PGM header: */
   fprintf(fp,"P5\n%d %d\n255\n", SIZE, SIZE);
  
   for(i = 0;i < SIZE; i++)
     for(j = 0;j < SIZE; j++) {
       c = space[i][j];
       fputc(c, fp);
     }
   fclose(fp);
 }