Very basic edid parse to check for audio support

edid_parser.c

#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>

#define HDMI_EDID_PATH "edid.bin"

#define ALOGE(...) (printf(__VA_ARGS__))

struct edid_extension {
    unsigned char tag;
    unsigned char rev;
    unsigned char dtd_offset;
    unsigned char info;
    unsigned char blocks[124];
};

struct edid {
    unsigned char stuff[126];
    unsigned char num_extensions;
    unsigned char checksum;
    struct edid_extension extensions[4]; // i guess there could be more but it's unlikely
};

static bool hdmi_supports_audio() {
    FILE *file;
    struct edid edid_data;
    int block_count, i;

    file = fopen(HDMI_EDID_PATH, "rb");
    if (file == NULL) {
        ALOGE("Unable to open EDID '%d'", HDMI_EDID_PATH);
        return false; // or should we fall back to true ?
    }

    fread(&edid_data, 1, sizeof(edid_data), file);
    fclose(file);

    ALOGE("NUM EXTENSIONS: %d\n", edid_data.num_extensions);
    for (i = 0; i < edid_data.num_extensions < 4 ? edid_data.num_extensions : 4; i++)
    {
        struct edid_extension *ext = &edid_data.extensions[i];
	ALOGE("extension tag: %u\n", ext->tag);
        if (ext->tag != 2)
            continue;
        if (ext->info & 0b01000000) // Bit 6 "display supports basic audio"
            return true;
    }

    return 0;
}

int main(int argc, char **argv) {
	bool supported = hdmi_supports_audio();
	ALOGE("supports audio: %d\n", supported);
}