1 files changed, 67 insertions, 0 deletions
diff --git a/src/pnm.c b/src/pnm.c
new file mode 100644
index 0000000..b2fa3c8
--- /dev/null
+++ b/src/pnm.c
@@ -0,0 +1,67 @@
+#include <string.h>
+
+#include "pnm.h"
+
+int
+readPnmHeader(FILE *fp, struct pnm *h) {
+	char line[1024];
+	char *lineptr;
+
+	memset(h, 0, sizeof(struct pnm));
+
+	lineptr = fgets(line, sizeof(line), fp);
+	if (!lineptr) {
+		fprintf(stderr, "premature end of pnm file\n");
+		return 1;
+	}
+
+	lineptr ++;
+
+	h->format = atoi(lineptr);
+	while (isdigit(*lineptr)) lineptr ++;
+
+	if (h->format == 7) lineptr = (char *)"";
+
+	while (lineptr != NULL && h->width == 0) {
+		if (*lineptr == '\0' || *lineptr == '#') {
+			lineptr = fgets(line, sizeof(line), fp);
+		} else if (isdigit(*lineptr)) {
+			h->width = strtol(lineptr, &lineptr, 10);
+		} else lineptr ++;
+	}
+
+	while (lineptr != NULL && h->height == 0) {
+		if (*lineptr == '\0' || *lineptr == '#') {
+			lineptr = fgets(line, sizeof(line), fp);
+		} else if (isdigit(*lineptr)) {
+			h->height = strtol(lineptr, &lineptr, 10);
+		} else lineptr ++;
+	}
+
+
+	if (h->format != 1 && h->format != 4) {
+		h->maxval = 0;
+
+		while (lineptr != NULL && h->maxval == 0) {
+			if (*lineptr == '\0' || *lineptr == '#') {
+				lineptr = fgets(line, sizeof(line), fp);
+			} else if (isdigit(*lineptr)) {
+				h->maxval = strtol(lineptr, &lineptr, 10);
+			} else lineptr ++;
+		}
+	} else {
+		h->maxval = 1;
+	}
+
+	return 0;
+}
+
+int
+writePnmHeader(FILE *fp, const struct pnm *h) {
+	fprintf(fp, "P%d\n", h->format);
+	fprintf(fp, "%d %d\n", h->width, h->height);
+	fprintf(fp, "%d\n", h->maxval);
+
+	return 0;
+}
+