edid/edid.h

#ifndef INCLUDED_MAX_EDID
#define INCLUDED_MAX_EDID

#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <stdlib.h>
#include "frozen/frozen.h"

#define EDID_LEN 128
#define EDID_DISPLAY_DESCRIPTOR_DATA_LEN 13

// EDID data structure

typedef  struct __attribute__ (( packed )) {
  uint8_t x_resolution;
  uint8_t vertical_frequency:6;
  uint8_t aspect_ratio      :2;
} standard_timing_information_t;

typedef struct __attribute__ (( packed )) {
  uint16_t pixel_clock;                           // 0-1
  uint8_t horizontal_active_pixels_lsbs;          // 2
  uint8_t horizontal_blanking_pixels_lsbs;        // 3
  uint8_t horizontal_blanking_pixels_msbs     :4; // 4
  uint8_t horizontal_active_pixels_msbs       :4;
  uint8_t vertical_active_lines_lsbs;             // 5
  uint8_t vertical_blanking_lines_lsbs;           // 6
  uint8_t vertical_blanking_lines_msbs        :4; // 7
  uint8_t vertical_active_lines_msbs          :4;
  uint8_t horizontal_front_porch_pixels_lsbs;     // 8
  uint8_t horizontal_sync_pulse_pixels_lsbs;      // 9
  uint8_t vertical_sync_pulse_lines_lsbs      :4; // 10
  uint8_t vertical_front_porch_lines_lsbs     :4;
  uint8_t vertical_sync_pulse_lines_msbs      :2; // 11
  uint8_t vertical_front_porch_lines_msbs     :2;
  uint8_t horizontal_sync_pulse_pixels_msbs   :2;
  uint8_t horizontal_front_porch_pixels_msbs  :2;
  uint8_t horizontal_image_size_lsbs;             // 12
  uint8_t vertical_image_size_lsbs;
  uint8_t vertical_image_size_msbs            :4;
  uint8_t horizontal_image_size_msbs          :4;
  uint8_t horizontal_border_pixels;
  uint8_t vertical_border_lines;
  // Feature bitmap
  union __attribute__ (( packed )) {
    struct __attribute__ (( packed )) {
      uint8_t stereo_mode_lsb                 :1;
      uint8_t sync_on_red_blue                :1;
      uint8_t vertical_sync_serration         :1;
      uint8_t sync_type                       :1;
      uint8_t analog_sync                     :1;
      uint8_t stereo_mode_msbs                :2;
      uint8_t interlaced                      :1;
    } analog;
    struct __attribute__ (( packed )) {
      uint8_t stereo_mode_lsb                 :1;
      uint8_t reserved                        :1;
      uint8_t vertical_sync_polarity          :1;
      uint8_t digital_composite_sync          :2;
      uint8_t stereo_mode_msbs                :2;
      uint8_t interlaced                      :1;
    } digital_composite;
    struct __attribute__ (( packed )) {
      uint8_t stereo_mode_lsb                 :1;
      uint8_t horizontal_sync_polarity        :1;
      uint8_t vertical_sync_serration         :1;
      uint8_t digital_seperate_sync           :2;
      uint8_t stereo_mode_msbs                :2;
      uint8_t interlaced                      :1;
    } digital_seperate;
  } features;
} detailed_timing_descriptor_t;

typedef struct __attribute__ (( packed )) {
  uint16_t display_descriptor;
  uint8_t reserved;
  uint8_t display_range_limits_descriptor;
  struct __attribute__ (( packed )) {
    uint8_t vertical    :2;
    uint8_t horizontal  :2;
    uint8_t reserved    :4;
  } rate_offsets;
  struct __attribute__ (( packed )) {
    uint8_t minimum;
    uint8_t maximum;
  } vertical_field_rate;
  struct __attribute__ (( packed )) {
    uint8_t minimum;
    uint8_t maximum;
  } horizontal_line_rate;
  uint8_t maximum_pixel_clock_mhz; // In 10 MHz units
  uint8_t extended_timing_information_type;
  uint8_t video_timing_params[7];
} range_limits_descriptor_t;

typedef struct __attribute__ (( packed )) {
  uint16_t display_descriptor;
  uint8_t reserved0;
  uint8_t descriptor_type;
  uint8_t reserved1;
  uint8_t descriptor_data[EDID_DISPLAY_DESCRIPTOR_DATA_LEN];
} display_descriptor_t;

typedef struct __attribute__ (( packed )) {
  /*! Header information, 20 bytes */
  struct __attribute__ (( packed )) {
    uint64_t preamble;
    uint8_t manufacturer_id[2];
    uint16_t product_code;
    uint32_t serial_number;
    uint8_t week_of_manufacture;
    uint8_t year_of_manufacture;
    uint8_t edid_version;
    uint8_t edid_revision;
  } header;
  /*! Basic display parameters, 5 bytes */
  struct __attribute__ (( packed )) {
    union __attribute__ (( packed )) {
      struct __attribute__ (( packed )) {
        uint8_t video_interface : 4;
        uint8_t bit_depth       : 3;
        uint8_t input_type      : 1; // 1 for digital
      } digital;
      struct __attribute__ (( packed )) {
        uint8_t vsync_serrated: 1;
        uint8_t sync_on_green : 1;
        uint8_t composite_sync: 1;
        uint8_t seperate_sync : 1;
        uint8_t blank_to_black: 1;
        uint8_t levels        : 2;
        uint8_t input_type    : 1; // 0 for analog
      } analog;
    } video_input_parameters; // 1 byte
    uint8_t horizontal_screen_size;
    uint8_t vertical_screen_size;
    uint8_t gamma;
    struct __attribute__ (( packed )) {
      uint8_t continuous_timings        : 1;
      uint8_t preferred_timing_mode     : 1;
      uint8_t standard_srgb             : 1;
      uint8_t display_type              : 2;
      uint8_t dpms_active_off_supported : 1;
      uint8_t dpms_suspend_supported    : 1;
      uint8_t dpms_standby_supported    : 1;
    } features;
  } basic_display_parameters;
  /*! Chromaticity coordinates. 10-bit CIE 1931 xy coordinates for red, green,
   *  blue, and white point, 10 bytes */
  struct __attribute__ (( packed )) {
    struct __attribute__ (( packed )) {
      uint8_t green_y : 2;
      uint8_t green_x : 2;
      uint8_t red_y   : 2;
      uint8_t red_x   : 2;
    } red_green_lsbs;
    struct __attribute__ (( packed )) {
      uint8_t white_y : 2;
      uint8_t white_x : 2;
      uint8_t blue_y  : 2;
      uint8_t blue_x  : 2;
    } blue_white_lsbs;
    uint8_t red_x_msbs;
    uint8_t red_y_msbs;
    uint8_t green_x_msbs;
    uint8_t green_y_msbs;
    uint8_t blue_x_msbs;
    uint8_t blue_y_msbs;
    uint8_t white_x_msbs;
    uint8_t white_y_msbs;
  } chromaticity_coordinates;
  /*! Established timing bitmap. Supported bitmap for (formerly) very common
      timing modes. 3 bytes */
  struct __attribute__ (( packed )) {
    uint8_t m800_600_60  : 1;
    uint8_t m800_600_56  : 1;
    uint8_t m640_480_75  : 1;
    uint8_t m640_480_72  : 1;
    uint8_t m640_480_67  : 1;
    uint8_t m640_480_60  : 1;
    uint8_t m720_400_88  : 1;
    uint8_t m720_400_70  : 1;
    uint8_t m1280_1024_75: 1;
    uint8_t m1024_768_75 : 1;
    uint8_t m1024_768_70 : 1;
    uint8_t m1024_768_60 : 1;
    uint8_t m1024_768_87 : 1;
    uint8_t m832_624_75  : 1;
    uint8_t m800_600_75  : 1;
    uint8_t m800_600_72  : 1;
    uint8_t reserved     : 7;
    uint8_t m1152_870_75 : 1;
  } common_timing_modes;
  /*! Standard timing information. Up to 8 2-byte fields describing standard
      display modes. Unused fields are filled with 01 01 hex. 16 bytes */
  standard_timing_information_t timings[8];
  detailed_timing_descriptor_t detailed_timing_descriptor;
  range_limits_descriptor_t range_limits_descriptor;
  display_descriptor_t display_name_descriptor;
  display_descriptor_t display_serial_number_descriptor;
  uint8_t number_extensions;
  uint8_t checksum;
} edid_t;

// Interface
int generate_edid(edid_t* const edid, const char* const filename);

#endif