edid.cpp

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/*
 * Copyright 2007 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: Soren Sandmann <sandmann@redhat.com> */
#include "edid.h"
#include <stdint.h>
#include <math.h>
#include <memory.h>
#include <X11/Xatom.h>


static int get_bit(int in, int bit) {
    return (in & (1 << bit)) >> bit;
}

static int get_bits(int in, int begin, int end) {
    int mask = (1 << (end - begin + 1)) - 1;

    return (in >> begin) & mask;
}

static bool decode_header(const uint8_t *edid) {
    if (memcmp(edid, "\x00\xff\xff\xff\xff\xff\xff\x00", 8) == 0)
        return true;
    return false;
}

static int decode_vendor_and_product_identification(const uint8_t *edid, MonitorInfo *info) {

    /* Manufacturer Code */
    info->manufacturer_code[0] = get_bits(edid[0x08], 2, 6);
    info->manufacturer_code[1] = get_bits(edid[0x08], 0, 1) << 3;
    info->manufacturer_code[1] |= get_bits(edid[0x09], 5, 7);
    info->manufacturer_code[2] = get_bits(edid[0x09], 0, 4);
    info->manufacturer_code[3] = '\0';

    info->manufacturer_code[0] += 'A' - 1;
    info->manufacturer_code[1] += 'A' - 1;
    info->manufacturer_code[2] += 'A' - 1;

    /* Product Code */
    info->product_code = edid[0x0b] << 8 | edid[0x0a];

    /* Serial Number */
    info->serial_number = edid[0x0c] | edid[0x0d] << 8 | edid[0x0e] << 16 | edid[0x0f] << 24;

    /* Week and Year */
    bool is_model_year = false;
    switch (edid[0x10]) {
    case 0x00:
        info->production_week = -1;
        break;

    case 0xff:
        info->production_week = -1;
        is_model_year = true;
        break;

    default:
        info->production_week = edid[0x10];
        break;
    }

    if (is_model_year) {
        info->production_year = -1;
        info->model_year = 1990 + edid[0x11];
    } else {
        info->production_year = 1990 + edid[0x11];
        info->model_year = -1;
    }

    return true;
}

static bool decode_edid_version(const uint8_t *edid, MonitorInfo *info) {
    info->major_version = edid[0x12];
    info->minor_version = edid[0x13];
    return true;
}

static bool decode_display_parameters(const uint8_t *edid, MonitorInfo *info) {
    /* Digital vs Analog */
    info->is_digital = get_bit(edid[0x14], 7);

    if (info->is_digital) {
        static const int bit_depth[8] = { -1, 6, 8, 10, 12, 14, 16, -1 };
        static const Interface interfaces[6] = { UNDEFINED, DVI, HDMI_A, HDMI_B, MDDI, DISPLAY_PORT };

        int bits = get_bits(edid[0x14], 4, 6);
        info->connector.digital.bits_per_primary = bit_depth[bits];

        bits = get_bits(edid[0x14], 0, 3);
        if (bits <= 5)
            info->connector.digital.interface = interfaces[bits];
        else
            info->connector.digital.interface = UNDEFINED;
    } else {
        int bits = get_bits(edid[0x14], 5, 6);
        static const double levels[][3] = { //
                { 0.7, 0.3, 1.0 }, //
                { 0.714, 0.286, 1.0 }, //
                { 1.0, 0.4, 1.4 }, //
                { 0.7, 0.0, 0.7 }, //
                };

        info->connector.analog.video_signal_level = levels[bits][0];
        info->connector.analog.sync_signal_level = levels[bits][1];
        info->connector.analog.total_signal_level = levels[bits][2];
        info->connector.analog.blank_to_black = get_bit(edid[0x14], 4);
        info->connector.analog.separate_hv_sync = get_bit(edid[0x14], 3);
        info->connector.analog.composite_sync_on_h = get_bit(edid[0x14], 2);
        info->connector.analog.composite_sync_on_green = get_bit(edid[0x14], 1);
        info->connector.analog.serration_on_vsync = get_bit(edid[0x14], 0);
    }

    /* Screen Size / Aspect Ratio */
    if (edid[0x15] == 0 && edid[0x16] == 0) {
        info->width_mm = -1;
        info->height_mm = -1;
        info->aspect_ratio = -1.0;
    } else if (edid[0x16] == 0) {
        info->width_mm = -1;
        info->height_mm = -1;
        info->aspect_ratio = 100.0 / (edid[0x15] + 99);
    } else if (edid[0x15] == 0) {
        info->width_mm = -1;
        info->height_mm = -1;
        info->aspect_ratio = 100.0 / (edid[0x16] + 99);
        info->aspect_ratio = 1 / info->aspect_ratio; /* portrait */
    } else {
        info->width_mm = 10 * edid[0x15];
        info->height_mm = 10 * edid[0x16];
    }

    /* Gamma */
    if (edid[0x17] == 0xFF)
        info->gamma = -1.0;
    else
        info->gamma = (edid[0x17] + 100.0) / 100.0;

    /* Features */
    info->standby = get_bit(edid[0x18], 7);
    info->suspend = get_bit(edid[0x18], 6);
    info->active_off = get_bit(edid[0x18], 5);

    if (info->is_digital) {
        info->connector.digital.rgb444 = 1;
        if (get_bit(edid[0x18], 3))
            info->connector.digital.ycrcb444 = 1;
        if (get_bit(edid[0x18], 4))
            info->connector.digital.ycrcb422 = 1;
    } else {
        int bits = get_bits(edid[0x18], 3, 4);
        ColorType color_type[4] = { MONOCHROME, RGB, OTHER_COLOR, UNDEFINED_COLOR };

        info->connector.analog.color_type = color_type[bits];
    }

    info->srgb_is_standard = get_bit(edid[0x18], 2);

    /* In 1.3 this is called "has preferred timing" */
    info->preferred_timing_includes_native = get_bit(edid[0x18], 1);

    /* FIXME: In 1.3 this indicates whether the monitor accepts GTF */
    info->continuous_frequency = get_bit(edid[0x18], 0);
    return true;
}

static double decode_fraction(int high, int low) {
    double result = 0.0;
    high = (high << 2) | low;
    for (int i = 0; i < 10; ++i)
        result += get_bit(high, i) * pow(2, i - 10);
    return result;
}

static bool decode_color_characteristics(const uint8_t *edid, MonitorInfo *info) {
    info->red_x = decode_fraction(edid[0x1b], get_bits(edid[0x19], 6, 7));
    info->red_y = decode_fraction(edid[0x1c], get_bits(edid[0x19], 5, 4));
    info->green_x = decode_fraction(edid[0x1d], get_bits(edid[0x19], 2, 3));
    info->green_y = decode_fraction(edid[0x1e], get_bits(edid[0x19], 0, 1));
    info->blue_x = decode_fraction(edid[0x1f], get_bits(edid[0x1a], 6, 7));
    info->blue_y = decode_fraction(edid[0x20], get_bits(edid[0x1a], 4, 5));
    info->white_x = decode_fraction(edid[0x21], get_bits(edid[0x1a], 2, 3));
    info->white_y = decode_fraction(edid[0x22], get_bits(edid[0x1a], 0, 1));

    return true;
}

static bool decode_established_timings(const uint8_t *edid, MonitorInfo *info) {
    static const Timing established[][8] = { //
            { { 800, 600, 60 }, { 800, 600, 56 }, //
              { 640, 480, 75 }, { 640, 480, 72 }, //
              { 640, 480, 67 }, { 640, 480, 60 }, //
              { 720, 400, 88 }, { 720, 400, 70 } }, //
            { { 1280, 1024, 75 }, { 1024, 768, 75 }, //
              { 1024, 768, 70 }, { 1024, 768, 60 }, //
              { 1024, 768, 87 }, { 832, 624, 75 }, //
              { 800, 600, 75 }, { 800, 600, 72 } }, //
            { { 0, 0, 0 }, { 0, 0, 0 }, { 0, 0, 0 }, { 0, 0, 0 }, //
              { 0, 0, 0 }, { 0, 0, 0 }, { 0, 0, 0 }, { 1152, 870, 75 } }, //
            };

    int idx = 0;
    for (int i = 0; i < 3; ++i) {
        for (int j = 0; j < 8; ++j) {
            int byte = edid[0x23 + i];

            if (get_bit(byte, j) && established[i][j].frequency != 0)
                info->established[idx++] = established[i][j];
        }
    }
    return true;
}

static bool decode_standard_timings(const uint8_t *edid, MonitorInfo *info) {
    int i;

    for (i = 0; i < 8; i++) {
        int first = edid[0x26 + 2 * i];
        int second = edid[0x27 + 2 * i];

        if (first != 0x01 && second != 0x01) {
            int w = 8 * (first + 31);
            int h = 0;

            switch (get_bits(second, 6, 7)) {
            case 0x00:
                h = (w / 16) * 10;
                break;
            case 0x01:
                h = (w / 4) * 3;
                break;
            case 0x02:
                h = (w / 5) * 4;
                break;
            case 0x03:
                h = (w / 16) * 9;
                break;
            }

            info->standard[i].width = w;
            info->standard[i].height = h;
            info->standard[i].frequency = get_bits(second, 0, 5) + 60;
        }
    }

    return true;
}

static void decode_lf_string(const uint8_t *s, int n_chars, char *result) {
    int i;
    for (i = 0; i < n_chars; ++i) {
        if (s[i] == 0x0a) {
            *result++ = '\0';
            break;
        } else if (s[i] == 0x00) {
            /* Convert embedded 0's to spaces */
            *result++ = ' ';
        } else {
            *result++ = s[i];
        }
    }
}

static void decode_display_descriptor(const uint8_t *desc, MonitorInfo *info) {
    switch (desc[0x03]) {
    case 0xFC:
        decode_lf_string(desc + 5, 13, info->dsc_product_name);
        break;
    case 0xFF:
        decode_lf_string(desc + 5, 13, info->dsc_serial_number);
        break;
    case 0xFE:
        decode_lf_string(desc + 5, 13, info->dsc_string);
        break;
    case 0xFD:
        /* Range Limits */
        break;
    case 0xFB:
        /* Color Point */
        break;
    case 0xFA:
        /* Timing Identifications */
        break;
    case 0xF9:
        /* Color Management */
        break;
    case 0xF8:
        /* Timing Codes */
        break;
    case 0xF7:
        /* Established Timings */
        break;
    case 0x10:
        break;
    }
}

static void decode_detailed_timing(const uint8_t *timing, DetailedTiming *detailed) {
    int bits;
    StereoType stereo[] = { //
            NO_STEREO, NO_STEREO, //
            FIELD_RIGHT, FIELD_LEFT, //
            TWO_WAY_RIGHT_ON_EVEN, TWO_WAY_LEFT_ON_EVEN, //
            FOUR_WAY_INTERLEAVED, //
            SIDE_BY_SIDE //
            };

    detailed->pixel_clock = (timing[0x00] | timing[0x01] << 8) * 10000;
    detailed->h_addr = timing[0x02] | ((timing[0x04] & 0xf0) << 4);
    detailed->h_blank = timing[0x03] | ((timing[0x04] & 0x0f) << 8);
    detailed->v_addr = timing[0x05] | ((timing[0x07] & 0xf0) << 4);
    detailed->v_blank = timing[0x06] | ((timing[0x07] & 0x0f) << 8);
    detailed->h_front_porch = timing[0x08] | get_bits(timing[0x0b], 6, 7) << 8;
    detailed->h_sync = timing[0x09] | get_bits(timing[0x0b], 4, 5) << 8;
    detailed->v_front_porch = get_bits(timing[0x0a], 4, 7) | get_bits(timing[0x0b], 2, 3) << 4;
    detailed->v_sync = get_bits(timing[0x0a], 0, 3) | get_bits(timing[0x0b], 0, 1) << 4;
    detailed->width_mm = timing[0x0c] | get_bits(timing[0x0e], 4, 7) << 8;
    detailed->height_mm = timing[0x0d] | get_bits(timing[0x0e], 0, 3) << 8;
    detailed->right_border = timing[0x0f];
    detailed->top_border = timing[0x10];
    detailed->interlaced = get_bit(timing[0x11], 7);

    /* Stereo */
    bits = get_bits(timing[0x11], 5, 6) << 1 | get_bit(timing[0x11], 0);
    detailed->stereo = stereo[bits];

    /* Sync */
    bits = timing[0x11];

    detailed->digital_sync = get_bit(bits, 4);
    if (detailed->digital_sync) {
        detailed->connector.digital.composite = !get_bit(bits, 3);
        if (detailed->connector.digital.composite) {
            detailed->connector.digital.serrations = get_bit(bits, 2);
            detailed->connector.digital.negative_vsync = 0;
        } else {
            detailed->connector.digital.serrations = 0;
            detailed->connector.digital.negative_vsync = !get_bit(bits, 2);
        }
        detailed->connector.digital.negative_hsync = !get_bit(bits, 0);
    } else {
        detailed->connector.analog.bipolar = get_bit(bits, 3);
        detailed->connector.analog.serrations = get_bit(bits, 2);
        detailed->connector.analog.sync_on_green = !get_bit(bits, 1);
    }
}

static bool decode_descriptors(const uint8_t *edid, MonitorInfo *info) {
    int timing_idx = 0;
    for (int i = 0; i < 4; ++i) {
        int index = 0x36 + i * 18;
        if (edid[index + 0] == 0x00 && edid[index + 1] == 0x00) {
            decode_display_descriptor(edid + index, info);
        } else {
            decode_detailed_timing(edid + index, &(info->detailed_timings[timing_idx++]));
        }
    }
    info->n_detailed_timings = timing_idx;
    return true;
}

static void decode_check_sum(const uint8_t *edid, MonitorInfo *info) {
    uint8_t check = 0;
    for (int i = 0; i < 128; ++i)
        check += edid[i];
    info->checksum = check;
}

MonitorInfo * decode_edid(const uint8_t *edid) {
    MonitorInfo *info = new MonitorInfo();
    decode_check_sum(edid, info);
    if (decode_header(edid) && //
            decode_vendor_and_product_identification(edid, info) && //
            decode_edid_version(edid, info) && //
            decode_display_parameters(edid, info) && //
            decode_color_characteristics(edid, info) && //
            decode_established_timings(edid, info) && //
            decode_standard_timings(edid, info) && //
            decode_descriptors(edid, info)) {
        return info;
    } else {
        delete info;
        return 0;
    }
}

static uint8_t * get_property(Display *dpy, RROutput output, Atom atom, int *len) {
    unsigned char *prop;
    int actual_format;
    unsigned long nitems, bytes_after;
    Atom actual_type;
    uint8_t *result = NULL;

    XRRGetOutputProperty(dpy, output, atom, 0, 100, False, False,
    AnyPropertyType, &actual_type, &actual_format, &nitems, &bytes_after, &prop);

    if (actual_type == XA_INTEGER && actual_format == 8) {
        result = new uint8_t[nitems];
        memcpy(result, prop, nitems);
        if (len)
            *len = nitems;
    }
    XFree(prop);
    return result;
}

MonitorInfo * read_edid_data(Display * disp, RROutput id) {
    int len;
    Atom edid_atom = XInternAtom(disp, "EDID", false);
    uint8_t *edid = get_property(disp, id, edid_atom, &len);
    if (!edid) {
        edid_atom = XInternAtom(disp, "EDID_DATA", false);
        edid = get_property(disp, id, edid_atom, &len);
    }

    MonitorInfo * result = 0;
    if (edid) {
        if (len % 128 == 0) {
            result = decode_edid(edid);
        }
        delete[] edid;
    }

    return result;
}