init: ppm library utilities implemented

It is not completed at all but it works well

3 files changed, 125 insertions, 0 deletions

diff --git a/src/main.c b/src/main.c
new file mode 100644
index 0000000..242e464
--- /dev/null
+++ b/src/main.c
@@ -0,0 +1,16 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "ppm.h"
+
+int main(int argc, char *argv[])
+{
+    Image img;
+    ppm_read("images/boxes_1.ppm", &img);
+
+    printf("width: %d\n", img.width);
+    printf("height: %d\n", img.height);
+    printf("bits: %d\n", img.pixel_bits);
+    printf("data[2]: %d\n", img.data[2]);
+    return 0;
+}
diff --git a/src/ppm.c b/src/ppm.c
new file mode 100644
index 0000000..f96e950
--- /dev/null
+++ b/src/ppm.c
@@ -0,0 +1,94 @@
+#include "ppm.h"
+
+static void read_header(FILE *fp, char ppm_type[2], int img_size[3]);
+static void read_p6_data(FILE *fp, Image *img);
+
+void
+ppm_write(const char *file, Image *img)
+{
+    FILE *fp = fopen(file, "w");
+
+    if (fp == NULL) {
+        perror("ppm_read() Error");
+        exit(1);
+    }
+
+    size_t n_pixels;
+
+    fprintf(fp, "P6\n%d %d\n%d\n", img->width, img->height, img->pixel_bits);
+    fwrite(img->data, n_pixels, sizeof(uint8_t), fp);
+    fclose(fp);
+}
+
+void
+ppm_read(const char *file, Image *img)
+    /*
+     * Read a ppm image
+     */
+{
+    FILE *fp = fopen(file, "r");
+
+    if (fp == NULL) {
+        perror("ppm_read() Error");
+        exit(1);
+    }
+
+    char ppm_type[3];
+    int img_size[3]; 
+
+    read_header(fp, ppm_type, img_size);
+    img->width = img_size[0];
+    img->height = img_size[1];
+    img->pixel_bits = img_size[2];
+
+    if (!strcmp(ppm_type, "P6")) read_p6_data(fp, img);
+    else {
+        fprintf(stderr, "ppm_read() Error: %s format not supported\n", ppm_type);
+        fclose(fp);
+        exit(1);
+    }
+    fclose(fp);
+}
+
+void
+read_header(FILE *fp, char ppm_type[2], int img_size[3])
+{
+    int i, n, ret;
+    char line_buffer[70], *buffer;
+
+    buffer = fgets(line_buffer, 70, fp);
+    for (i = n = 0; i < 4; ) {
+
+        if (i == 0) {
+            sscanf(line_buffer, "%2s%n", ppm_type, &n);
+            buffer += n;
+            i++;
+        }
+
+        else if (i > 0) {
+            ret = sscanf(buffer, "%d%n", img_size + i - 1, &n);
+            if (ret >= 1) {
+                buffer += n;
+                i++;
+            } else buffer = fgets(line_buffer, 70, fp); 
+        }
+    }
+}
+
+void
+read_p6_data(FILE *fp, Image *img)
+{
+    int n_pixels = img->width * img->height * 3;
+    img->data = calloc(n_pixels, sizeof(uint8_t));
+
+    if (img->data == NULL) {
+        perror("read_p6_data() Error");
+        exit(1);
+    }
+
+    fread(img->data, n_pixels, sizeof(uint8_t), fp);
+    if (ferror(fp)) {
+        perror("read_p6_data() Error");
+        exit(1);
+    }
+}
diff --git a/src/ppm.h b/src/ppm.h
new file mode 100644
index 0000000..5cf8b02
--- /dev/null
+++ b/src/ppm.h
@@ -0,0 +1,15 @@
+#ifndef __PPM__
+#define __PPM__
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+typedef struct Image {
+    uint8_t *data;
+    int32_t width, height, pixel_bits;
+} Image;
+
+void ppm_read(const char *file, Image *img);
+void ppm_write(const char *file, Image *img);
+#endif