Initial import. More or less works!

.gitignore

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+edid-decode
+*.jx

Makefile

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+# ZSH OR DIE, PUNKS
+
+edid-decode: edid-decode.c
+	gcc -O2 -Wall -o $@ $<
+
+clean:
+	-echo rm -f edid-decode **/*.jx | zsh -s

edid-decode.c

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+/*
+ * Copyright 2006 Red Hat, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * on the rights to use, copy, modify, merge, publish, distribute, sub
+ * license, and/or sell copies of the Software, and to permit persons to whom
+ * the Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+/* Author: Adam Jackson <ajax@nwnk.net> */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+
+/* booleans for determining 1.3 conformance */
+int claims_one_point_two = 0;
+int claims_one_point_three = 0;
+int conformant_digital_display = 0;
+int did_detailed_timing = 0;
+int has_name_descriptor = 0;
+int has_range_descriptor = 0;
+int has_preferred_timing = 0;
+int has_valid_checksum = 0;
+
+static char *manufacturer_name(unsigned char *x)
+{
+    static char name[4];
+
+    name[0] = ((x[0] & 0x7C) >> 2) + '@';
+    name[1] = ((x[0] & 0x03) << 3) + ((x[1] & 0xE0) >> 5) + '@';
+    name[2] = (x[1] & 0x1F) + '@';
+    name[3] = 0;
+
+    return name;
+}
+
+static void
+detailed_block(unsigned char *x)
+{
+    static unsigned char name[53];
+    int ha, hbl, hso, hspw, hborder, va, vbl, vso, vspw, vborder;
+
+    if (!x[0] && !x[1] && !x[2] && !x[4]) {
+	switch (x[3]) {
+	case 0x10:
+	    printf("Dummy block\n");
+	    return;
+	case 0xFA:
+	    printf("More standard timings\n");
+	    return;
+	case 0xFB:
+	    printf("Color point\n");
+	    return;
+	case 0xFC:
+	    has_name_descriptor = 1;
+	    if (strchr((char *)name, '\n')) return;
+	    strncat((char *)name, (char *)x + 5, 12);
+	    if (strchr((char *)name, '\n'))
+		printf("Monitor name: %s", name);
+	    return;
+	case 0xFD:
+	    has_range_descriptor = 1;
+	    printf("Monitor ranges\n");
+	    return;
+	case 0xFE:
+	    printf("ASCII string\n");
+	    return;
+	case 0xFF:
+	    printf("Serial number\n");
+	    return;
+	default:
+	    printf("Unknown monitor description type %d\n", x[3]);
+	    return;
+	}
+    }
+
+    did_detailed_timing = 1;
+    ha = (x[2] + ((x[4] & 0xF0) << 4));
+    hbl = (x[3] + ((x[4] & 0x0F) << 8));
+    hso = (x[8] + ((x[11] & 0xC0) << 2));
+    hspw = (x[9] + ((x[11] & 0x30) << 4));
+    hborder = x[15];
+    va = (x[5] + ((x[7] & 0xF0) << 4));
+    vbl = (x[6] + ((x[7] & 0x0F) << 8));
+    vso = ((x[10] >> 4) + ((x[11] & 0x0C) << 2));
+    vspw = ((x[10] & 0x0F) + ((x[11] & 0x03) << 4));
+    vborder = x[16];
+
+    printf("Detailed mode: Clock %.3f MHz, %d mm x %d mm\n"
+	   "               ha %d hbl %d hso %d hspw %d hborder %d\n"
+	   "               va %d vbl %d vso %d vspw %d vborder %d\n",
+	    (x[0] + (x[1] << 8)) / 100.0,
+	    (x[12] + ((x[14] & 0xF0) << 4)),
+	    (x[13] + ((x[14] & 0x0F) << 8)),
+	    ha, hbl, hso, hspw, hborder, va, vbl, vso, vspw, vborder
+	  );
+    /* XXX flag decode */
+}
+
+int main(int argc, char **argv)
+{
+    int fd;
+    unsigned char edid[128];
+    if (argc != 2) {
+	printf("Need a file name\n");
+	return 1;
+    }
+
+    if ((fd = open(argv[1], O_RDONLY)) == -1) {
+	printf("Open failed\n");
+	return 1;
+    }
+
+    read(fd, edid, 128);
+    close(fd);
+
+    if (memcmp(edid, "\x00\xFF\xFF\xFF\xFF\xFF\xFF\x00", 8)) {
+	printf("No header found\n");
+	return 1;
+    }
+
+    printf("Manufacturer: %s Model %x Serial Number %u\n",
+	    manufacturer_name(edid + 0x08),
+	    (unsigned short)edid[0x0A],
+	    (unsigned int)edid[0x0C]);
+    if (edid[0x11])
+	printf("Made week %hd of %hd\n", edid[0x10], edid[0x11]);
+    else
+	printf("No manufacture date given\n");
+    printf("EDID version: %hd.%hd\n", edid[0x12], edid[0x13]);
+    if (edid[0x12] == 1) {
+	if (edid[0x13] > 3) {
+	    printf("Claims > 1.3, assuming 1.3 conformance\n");
+	    edid[0x13] = 3;
+	}
+	switch (edid[0x13]) {
+	case 3:
+	    claims_one_point_three = 1;
+	case 2:
+	    claims_one_point_two = 1;
+	default:
+	    break;
+	}
+    }
+
+    /* display section */
+
+    if (edid[0x14] & 0x80) {
+	int conformance_mask = claims_one_point_two ? 0x7E : 0x7F;
+	printf("Digital display\n");
+	if (claims_one_point_two) {
+	    if (edid[0x14] & 0x01) {
+		printf("DFP 1.x compatible TMDS\n");
+	    }
+	}
+	if (!(edid[0x14] & conformance_mask))
+	    conformant_digital_display = 1;
+    } else {
+	int voltage = (edid[0x14] & 0x60) >> 5;
+	int sync = (edid[0x14] & 0x0F);
+	printf("Analog display, Input voltage level: %s V\n",
+	       voltage == 3 ? "0.7/0.7" :
+	       voltage == 2 ? "1.0/0.4" :
+	       voltage == 1 ? "0.714/0.286" :
+	       "0.7/0.3");
+	if (edid[0x14] & 0x10)
+	    printf("Configurable signal levels\n");
+	printf("Sync: %s%s%s%s\n", sync & 0x08 ? "Separate " : "",
+	       sync & 0x04 ? "Composite " : "",
+	       sync & 0x02 ? "SyncOnGreen " : "",
+	       sync & 0x01 ? "Serration " : "");
+    }
+
+    if (edid[0x15] && edid[0x16])
+	printf("Maximum image size: %d cm x %d cm\n", edid[0x15], edid[0x16]);
+    else
+	printf("Maximum image size is variable\n");
+
+    printf("Gamma: %.2f\n",
+	    edid[0x17] == 0xff ? 1.0 : ((edid[0x17] + 100.0) / 100.0));
+
+    if (edid[0x18] & 0xE0) {
+	printf("DPMS levels:");
+	if (edid[0x18] & 0x80) printf(" Standby");
+	if (edid[0x18] & 0x40) printf(" Suspend");
+	if (edid[0x18] & 0x20) printf(" Off");
+	printf("\n");
+    }
+
+    if (edid[0x18] & 0x10)
+	printf("Non-RGB color display\n");
+    else if (edid[0x18] & 0x08)
+	printf("RGB color display\n");
+    else
+	printf("Monochrome or grayscale display\n");
+
+    if (edid[0x18] & 0x04)
+	printf("Default color space is primary color space\n");
+    if (edid[0x18] & 0x02) {
+	printf("First detailed timing is preferred timing\n");
+	has_preferred_timing = 1;
+    }
+    if (edid[0x18] & 0x01)
+	printf("Supports GTF timings within operating range\n");
+
+    /* XXX color section */
+
+    /* XXX established timings */
+
+    /* XXX standard timings */
+
+    /* detailed timings */
+    detailed_block(edid + 0x36);
+    if (has_preferred_timing && !did_detailed_timing)
+	has_preferred_timing = 0; /* not really accurate... */
+    detailed_block(edid + 0x48);
+    detailed_block(edid + 0x5A);
+    detailed_block(edid + 0x6C);
+
+    if (edid[0x7e])
+	printf("Has %d extension blocks\n", edid[0x7e]);
+
+    printf("Checksum: 0x%hx\n", edid[0x7f]);
+    {
+	unsigned char sum = 0;
+	int i;
+	for (i = 0; i < 128; i++)
+	    sum += edid[i];
+	has_valid_checksum = !sum;
+    }
+    if (!has_valid_checksum)
+	printf("Block has broken checksum!\n");
+
+    if (claims_one_point_three) {
+	if (!conformant_digital_display ||
+	    !has_name_descriptor ||
+	    !has_preferred_timing ||
+	    !has_range_descriptor)
+	    printf("EDID block does NOT conform to EDID 1.3!\n");
+    } else if (claims_one_point_two) {
+	if (!conformant_digital_display)
+	    printf("EDID block does NOT conform to EDID 1.2!\n");
+    }
+
+    return 0;
+}