Initial version

3 files changed, 133 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..ecc2344
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+hexdiff
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..1a85bee
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,19 @@
+PREFIX ?= /usr/local
+BINDIR ?= /bin
+
+CFLAGS = -O2 -g
+
+all: hexdiff
+
+clean:
+	rm -f hexdiff
+
+hexdiff: hexdiff.c
+
+install:
+	install -m755 hexdiff -t "$(DESTDIR)$(PREFIX)$(BINDIR)"
+
+uninstall:
+	rm -f "$(DESTDIR)$(PREFIX)$(BINDIR)/hexdiff"
+
+.PHONY: all clean install uninstall
diff --git a/hexdiff.c b/hexdiff.c
new file mode 100644
index 0000000..1f34efc
--- /dev/null
+++ b/hexdiff.c
@@ -0,0 +1,113 @@
+#include <err.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <stdlib.h>
+
+struct file {
+	const char *fname;
+	FILE *file;
+	uint8_t buf[16];
+	size_t buflen;
+};
+
+const int equal_gradient[256] = {
+	[0] = 241,
+	[1 ... 31] = 242,
+	[32 ... 63] = 244,
+	[64 ... 95] = 246,
+	[96 ... 127] = 247,
+	[128 ... 159] = 248,
+	[160 ... 191] = 250,
+	[192 ... 223] = 252,
+	[224 ... 254] = 254,
+	[255] = 255,
+};
+
+const int diff_gradient[256] = {
+	[0] = 52,
+	[1 ... 95] = 88,
+	[96 ... 159] = 124,
+	[160 ... 223] = 160,
+	[224 ... 255] = 196,
+};
+
+bool use_color;
+bool has_color;
+
+static inline void
+color_byte(uint8_t b1, uint8_t b2)
+{
+	if (b1 != b2)
+		printf("\x1b[38:5:%um", diff_gradient[b1]);
+	else
+		printf("\x1b[38:5:%um", equal_gradient[b1]);
+	has_color = true;
+}
+
+static inline void
+color_clear(void)
+{
+	printf("\x1b[0m");
+}
+
+int
+main(int argc, const char **argv)
+{
+	struct file f1, f2;
+	const char **arg;
+	size_t pos, i;
+
+	memset(&f1, 0, sizeof(f1));
+	memset(&f2, 0, sizeof(f2));
+
+	has_color = false;
+	use_color = true;
+	for (arg = &argv[1]; *arg; arg++) {
+		if (!strcmp(*arg, "-c")) {
+			use_color = true;
+		} else if (!strcmp(*arg, "-C")) {
+			use_color = false;
+		} else if (!f1.fname) {
+			f1.fname = *arg;
+		} else if (!f2.fname) {
+			f2.fname = *arg;
+		} else {
+			fprintf(stderr, "Usage: hexdiff [-c] FILE FILE\n");
+			return 1;
+		}
+	}
+
+	f1.file = fopen(f1.fname, "r");
+	if (!f1.file) err(1, "fopen %s", f1.fname);
+
+	f2.file = fopen(f2.fname, "r");
+	if (!f2.file) err(1, "fopen %s", f2.fname);
+
+	pos = 0;
+	while (!feof(f1.file) && !feof(f2.file)) {
+		f1.buflen = fread(f1.buf, 1, 16, f1.file);
+		f2.buflen = fread(f2.buf, 1, 16, f2.file);
+		if (!f1.buflen && !f2.buflen) break;
+
+		printf("%06lx: ", pos);
+		for (i = 0; i < 16; i++) {
+			if (use_color) color_byte(f1.buf[i], f2.buf[i]);
+			printf("%02x ", f1.buf[i]);
+			if (has_color) color_clear();
+		}
+		printf("| ");
+		for (i = 0; i < 16; i++) {
+			if (use_color) color_byte(f2.buf[i], f1.buf[i]);
+			printf("%02x ", f2.buf[i]);
+			if (has_color) color_clear();
+		}
+		printf("\n");
+
+		pos += 16;
+	}
+
+	fclose(f1.file);
+	fclose(f2.file);
+}