pgm.h

#ifndef _PGM_H_
#define _PGM_H_

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

#define PGM_MAGIC "P5"

#ifdef _WIN32
#define STRTOK_R(ptr, del, saveptr) strtok_s(ptr, del, saveptr)
#else
#define STRTOK_R(ptr, del, saveptr) strtok_r(ptr, del, saveptr)
#endif

typedef struct _pgm_t {
        int width;
        int height;
        unsigned char *buf;
} pgm_t;

int readPGM(pgm_t *pgm, const char *filename) {
        char *token, *pc, *saveptr;
        char *buf;
        size_t bufsize;
        char del[] = " \t\n";
        unsigned char *dot;

        long begin, end;
        int filesize;
        int i, w, h, luma, pixs;

        FILE *fp;
        if ((fp = fopen(filename, "rb")) == NULL) {
                fprintf(stderr, "Failed to open file\n");
                return -1;
        }

        fseek(fp, 0, SEEK_SET);
        begin = ftell(fp);
        fseek(fp, 0, SEEK_END);
        end = ftell(fp);
        filesize = (int)(end - begin);

        buf = (char *)malloc(filesize * sizeof(char));
        fseek(fp, 0, SEEK_SET);
        bufsize = fread(buf, filesize * sizeof(char), 1, fp);

        fclose(fp);

        token = (char *)STRTOK_R(buf, del, &saveptr);
        if (strncmp(token, PGM_MAGIC, 2) != 0) {
                return -1;
        }

        token = (char *)STRTOK_R(NULL, del, &saveptr);
        if (token[0] == '#') {
                token = (char *)STRTOK_R(NULL, "\n", &saveptr);
                token = (char *)STRTOK_R(NULL, del, &saveptr);
        }

        w = strtoul(token, &pc, 10);
        token = (char *)STRTOK_R(NULL, del, &saveptr);
        h = strtoul(token, &pc, 10);
        token = (char *)STRTOK_R(NULL, del, &saveptr);
        luma = strtoul(token, &pc, 10);

        token = pc + 1;
        pixs = w * h;

        pgm->buf = (unsigned char *)malloc(pixs * sizeof(unsigned char));

        dot = pgm->buf;

        for (i = 0; i < pixs; i++, dot++) {
                *dot = *token++;
        }

        pgm->width = w;
        pgm->height = h;

        return 0;
}

int writePGM(pgm_t *pgm, const char *filename) {
        int i, w, h, pixs;
        FILE *fp;
        unsigned char *dot;

        w = pgm->width;
        h = pgm->height;
        pixs = w * h;

        if ((fp = fopen(filename, "wb+")) == NULL) {
                fprintf(stderr, "Failed to open file\n");
                return -1;
        }

        fprintf(fp, "%s\n%d %d\n255\n", PGM_MAGIC, w, h);

        dot = pgm->buf;

        for (i = 0; i < pixs; i++, dot++) {
                putc((unsigned char)*dot, fp);
        }

        fclose(fp);

        return 0;
}

int normalizeD2PGM(pgm_t *pgm, double *x) {
        int i, j, w, h;

        w = pgm->width;
        h = pgm->height;

        pgm->buf = (unsigned char *)malloc(w * h * sizeof(unsigned char));

        double min = 0;
        double max = 0;
        for (i = 0; i < h; i++) {
                for (j = 0; j < w; j++) {
                        if (max < x[i * w + j])
                                max = x[i * w + j];
                        if (min > x[i * w + j])
                                min = x[i * w + j];
                }
        }

        for (i = 0; i < h; i++) {
                for (j = 0; j < w; j++) {
                        if ((max - min) != 0)
                                pgm->buf[i * w + j] =
                                    (unsigned char)(255 * (x[i * w + j] - min) /
                                                    (max - min));
                        else
                                pgm->buf[i * w + j] = 0;
                }
        }

        return 0;
}

int normalizeF2PGM(pgm_t *pgm, float *x) {
        int i, j, w, h;

        w = pgm->width;
        h = pgm->height;

        pgm->buf = (unsigned char *)malloc(w * h * sizeof(unsigned char));

        float min = 0;
        float max = 0;
        for (i = 0; i < h; i++) {
                for (j = 0; j < w; j++) {
                        if (max < x[i * w + j])
                                max = x[i * w + j];
                        if (min > x[i * w + j])
                                min = x[i * w + j];
                }
        }

        for (i = 0; i < h; i++) {
                for (j = 0; j < w; j++) {
                        if ((max - min) != 0)
                                pgm->buf[i * w + j] =
                                    (unsigned char)(255 * (x[i * w + j] - min) /
                                                    (max - min));
                        else
                                pgm->buf[i * w + j] = 0;
                }
        }

        return 0;
}

int destroyPGM(pgm_t *pgm) {
        if (pgm->buf) {
                free(pgm->buf);
        }

        return 0;
}

#endif /* _PGM_H_ */