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commit ec9fce1544347f2c7ddc41d7de1d411dbaf00a69
parent 2d98ea2e90d1b6a8211df1798acb0d93fb9f252f
Author: Laslo Hunhold <dev@frign.de>
Date:   Fri, 14 Apr 2017 21:49:12 +0200

Update invert.c according to repo-changes

It was my interest to create an example that is not just an
artificial demonstration, but that can actually be used in
"production". This bloats the code up a bit, but with the comments
and so on it actually gets much more readable.

The 0BSD allows use without any strings attached.

Diffstat:
M
tools.suckless.org/farbfeld/invert.c
 | 
98
+++++++++++++++++++++++++++++++++++++++++++++++++++----------------------------

1 file changed, 63 insertions(+), 35 deletions(-)
diff --git a/tools.suckless.org/farbfeld/invert.c b/tools.suckless.org/farbfeld/invert.c
@@ -1,29 +1,52 @@
 /*
- * Copy me if you can.
- * by FRIGN
+ * 0BSD-License
+ *
+ * (c) 2017 Laslo Hunhold <dev@frign.de>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for
+ * any purpose with or without fee is hereby granted.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
+ * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
+ * AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
+ * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
+ * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
  */
 #include <arpa/inet.h>
 
+#include <errno.h>
 #include <stdint.h>
 #include <stdio.h>
-#include <stdlib.h>
 #include <string.h>
 
+#define LEN(x) (sizeof (x) / sizeof *(x))
+
+static void
+invert(uint16_t rgba[4])
+{
+	rgba[0] = UINT16_MAX - rgba[0];
+	rgba[1] = UINT16_MAX - rgba[1];
+	rgba[2] = UINT16_MAX - rgba[2];
+}
+
 int
 main(int argc, char *argv[])
 {
-	uint64_t rowlen;
-	uint32_t hdr[4], width, height, i, j;
-	uint16_t *row, *rgba;
+	uint32_t hdr[4], width, height, i, j, k;
+	uint16_t rgba[4];
 
-	if (argc > 1) {
+	/* arguments */
+	if (argc != 1) {
 		fprintf(stderr, "usage: %s\n", argv[0]);
 		return 1;
 	}
 
-	if (fread(hdr, sizeof(uint32_t), 4, stdin) != 4) {
-		fprintf(stderr, "%s: fread error\n", argv[0]);
-		return 1;
+	/* read header */
+	if (fread(hdr, sizeof(*hdr), LEN(hdr), stdin) != LEN(hdr)) {
+		goto readerr;
 	}
 	if (memcmp("farbfeld", hdr, sizeof("farbfeld") - 1)) {
 		fprintf(stderr, "%s: invalid magic value\n", argv[0]);
@@ -32,40 +55,45 @@ main(int argc, char *argv[])
 	width = ntohl(hdr[2]);
 	height = ntohl(hdr[3]);
 
-	if (fwrite(hdr, sizeof(uint32_t), 4, stdout) != 4) {
-		fprintf(stderr, "%s: fwrite error\n", argv[0]);
-		return 1;
+	/* write data */
+	if (fwrite(hdr, sizeof(*hdr), LEN(hdr), stdout) != 4) {
+		goto writerr;
 	}
 
-	rowlen = (sizeof("RGBA") - 1) * width;
-	if (!(row = malloc(rowlen * sizeof(uint16_t)))) {
-		fprintf(stderr, "%s: malloc: out of memory\n", argv[0]);
-		return 1;
-	}
 	for (i = 0; i < height; i++) {
-		if (fread(row, sizeof(uint16_t), rowlen, stdin) != rowlen) {
-			fprintf(stderr, "%s: fread error\n", argv[0]);
-			return 1;
-		}
-		for (rgba = row; (rgba - row) < rowlen; rgba += 4) {
-			for (j = 0; j < 4; j++) {
-				rgba[j] = ntohs(rgba[j]);
+		for (j = 0; j < width; j++) {
+			if (fread(rgba, sizeof(*rgba), LEN(rgba),
+			          stdin) != LEN(rgba)) {
+				goto readerr;
+			}
+			for (k = 0; k < 4; k++) {
+				rgba[k] = ntohs(rgba[k]);
 			}
 
-			/* invert colors */
-			rgba[0] = 65535 - rgba[0];
-			rgba[1] = 65535 - rgba[1];
-			rgba[2] = 65535 - rgba[2];
+			invert(rgba);
 
-			for (j = 0; j < 4; j++) {
-				rgba[j] = htons(rgba[j]);
+			for (k = 0; k < 4; k++) {
+				rgba[k] = htons(rgba[k]);
+			}
+			if (fwrite(rgba, sizeof(*rgba), LEN(rgba),
+			           stdout) != LEN(rgba)) {
+				goto writerr;
 			}
 		}
-		if (fwrite(row, sizeof(uint16_t), rowlen, stdout) != rowlen) {
-			fprintf(stderr, "%s: fwrite error\n", argv[0]);
-			return 1;
-		}
+	}
+
+	/* clean up */
+	if (fclose(stdout)) {
+		fprintf(stderr, "%s: fclose: %s\n", argv[0],
+		        strerror(errno));
+		return 1;
 	}
 
 	return 0;
+readerr:
+	fprintf(stderr, "%s: fread: Unexpected EOF\n", argv[0]);
+	return 1;
+writerr:
+	fprintf(stderr, "%s: fwrite: %s\n", argv[0], strerror(errno));
+	return 1;
 }