edid/main.c

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

#define EDID_LENGTH 128
#define EDID_BYTES_OFFSET_HEADER_PREAMBLE 0
#define EDID_BYTES_OFFSET_HEADER_MANUFACTURER_ID 8
#define EDID_BYTES_OFFSET_HEADER_PRODUCT_CODE 10

enum edid_analog_display_t {
  EDID_DISPLAY_TYPE_MONOCHROME_OR_GRAYSCALE = 0,
  EDID_DISPLAY_TYPE_RGB_COLOR               = 1,
  EDID_DISPLAY_TYPE_NON_RGB_COLOR           = 2,
  EDID_DISPLAY_TYPE_UNDEFINED               = 3
};

typedef  struct __attribute__ (( packed )) {
  uint8_t resolution;
  uint8_t image_aspect_ratio : 2;
  uint8_t vertical_frequency : 6;
} standard_timing_information_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 red_x   : 2;
      uint8_t red_y   : 2;
      uint8_t green_x : 2;
      uint8_t green_y : 2;
    } red_green_lsbs;
    struct __attribute__ (( packed )) {
      uint8_t blue_x  : 2;
      uint8_t blue_y  : 2;
      uint8_t white_x : 2;
      uint8_t white_y : 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;
  } chromacity_cordinates;
  /*! Established timing bitmap. Supported bitmap for (formerly) very common
      timing modes. 3 bytes */
  struct __attribute__ (( packed )) {
    uint8_t m720_400_70  : 1;
    uint8_t m720_400_80  : 1;
    uint8_t m640_480_60  : 1;
    uint8_t m640_480_67  : 1;
    uint8_t m640_480_72  : 1;
    uint8_t m640_480_75  : 1;
    uint8_t m800_600_56  : 1;
    uint8_t m800_600_60  : 1;
    uint8_t m800_600_72  : 1;
    uint8_t m800_600_75  : 1;
    uint8_t m832_624_75  : 1;
    uint8_t m1024_768_87 : 1;
    uint8_t m1024_768_60 : 1;
    uint8_t m1024_768_70 : 1;
    uint8_t m1024_768_75 : 1;
    uint8_t m1280_1024_75: 1;
    uint8_t m1152_870_75 : 1;
    uint8_t reserved     : 7;
  } 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];
  uint8_t descriptor_1[18];
  uint8_t descriptor_2[18];
  uint8_t descriptor_3[18];
  uint8_t descriptor_4[18];
  uint8_t number_extensions;
  uint8_t checksum;
} edid_t;

/**
 * @brief test function to show buffer
 */
static void disp_buf(uint8_t *buf, int len)
{
    int i;
    for (i = 0; i < len; i++) {
        printf("%02x ", buf[i]);
        if ((i + 1) % 16 == 0) {
            printf("\n");
        }
    }
    printf("\n");
}

static size_t file_to_str(unsigned char** str, const char const* filename)
{
  size_t length;
  FILE * f = fopen (filename, "rb");

  if (f) {
    fseek (f, 0, SEEK_END);
    length = ftell (f);
    fseek (f, 0, SEEK_SET);
    *str = (unsigned char*)malloc(length);
    if (*str) {
      fread (*str, 1, length, f);
    }
    fclose (f);
  } else {
    printf("File pointer is NULL..\n");
  }
  return length;
}

static void generate_preamble(edid_t* edid)
{
  memset((uint8_t*)&(edid->header.preamble)+0, 0x00, 1);
  memset((uint8_t*)&(edid->header.preamble)+1, 0xFF, 6);
  memset((uint8_t*)&(edid->header.preamble)+7, 0x00, 1);
/*memset( edid + EDID_BYTES_OFFSET_HEADER_PREAMBLE,
          0x00, 1);
  memset( edid + EDID_BYTES_OFFSET_HEADER_PREAMBLE + 1,
          0xFF, 6);
  memset( edid + EDID_BYTES_OFFSET_HEADER_PREAMBLE + 7,
          0x00, 1);
*/
}

static int generate_header(edid_t* edid, unsigned char* json_str, size_t json_len)
{
  char* multi_use_str;
  unsigned int multi_use_int;

  if (edid && json_str) {
    // Manufacturer ID
    json_scanf( json_str, json_len, "{header: {manufacturer_id: %Q}",
                &multi_use_str);
    if (strlen(multi_use_str) == 3) {
      multi_use_int = 0;
      multi_use_int |=
      ((0x1F & (multi_use_str[0]-64)) << 10)|        // First letter
      ((0x1F & (multi_use_str[1]-64)) << 5) |        // Second letter
      ((0x1F & (multi_use_str[2]-64)) << 0);         // Third letter
      edid->header.manufacturer_id[0] = multi_use_int >> 8;
      edid->header.manufacturer_id[1] = multi_use_int;
    } else {
      printf("Error: JSON file format is wrong somewhere arround manufacturer\
              ID.\n");
      return 1;
    }
    // %Q mallocs a string
    free(multi_use_str);
    // Product code
    json_scanf(json_str, json_len, "{header: {product_code: %d}", &multi_use_int);
    edid->header.product_code = 0xFFFF & multi_use_int;
    // Serial number
    json_scanf(json_str, json_len, "{header: {serial_number: %d}", &multi_use_int);
    edid->header.serial_number = 0xFFFFFFFF & multi_use_int;
    // Week of manufacture
    json_scanf( json_str, json_len, "{header: {week_of_manufacture: %d}",
                &multi_use_int);
    edid->header.week_of_manufacture = 0xFF & multi_use_int;
    // Year of manufacture
    json_scanf( json_str, json_len, "{header: {year_of_manufacture: %d}",
                &multi_use_int);
    edid->header.year_of_manufacture = 0xFF & (multi_use_int - 1990);
    // EDID version
    json_scanf(json_str, json_len, "{header: {edid_version: %d}", &multi_use_int);
    edid->header.edid_version = 0xFF & multi_use_int;
    // EDID revision
    json_scanf(json_str, json_len, "{header: {edid_revision: %d}", &multi_use_int);
    edid->header.edid_revision = 0xFF & multi_use_int;
  } else {
    printf("One of either edid or json_str is NULL.\n");
    return 2;
  }
  return 0;
}

static int generate_basic_display_parameters( edid_t* edid,
                                              unsigned char* json_str,
                                              size_t json_len)
{
  char* multi_use_str;
  float multi_use_flt0;
  float multi_use_flt1;
  unsigned int multi_use_int;
  bool multi_use_bool;

  if (edid && json_str) {
    // Input type analog or digital
    json_scanf( json_str, json_len, "{video_input_parameters: {input_type: %Q}",
                &multi_use_str);
    if (strcmp(multi_use_str, "analog") == 0) {
      edid->basic_display_parameters.video_input_parameters
        .analog.input_type = 0;
      // Levels
      json_scanf( json_str, json_len,
                  "{video_input_parameters: {levels: {upper: %f}}}",
                  &multi_use_flt0);
      json_scanf( json_str, json_len,
                  "{video_input_parameters: {levels: {lower: %f}}}",
                  &multi_use_flt1);
      if (multi_use_flt0 == 0.7f && multi_use_flt1 == -0.3f) {
        multi_use_int = 0;
      } else if (multi_use_flt0 == 0.714f && multi_use_flt1 == -0.286f) {
        multi_use_int = 1;
      } else if (multi_use_flt0 == 1.0f && multi_use_flt1 == -0.4f) {
        multi_use_int = 2;
      } else if (multi_use_flt0 == 0.7f && multi_use_flt1 == 0.0f) {
        multi_use_int = 3;
      } else {
        printf("Error: The levels %f/%f are not conforming to the standard.\n",
                multi_use_flt0, multi_use_flt1);
      }
      edid->basic_display_parameters.video_input_parameters
        .analog.levels = 0x3 & multi_use_int;
      // Blank to black
      json_scanf( json_str, json_len,
                  "{video_input_parameters: {blank_to_black: %B}}",
                  &multi_use_bool);
      edid->basic_display_parameters.video_input_parameters
        .analog.blank_to_black = 0x1 & multi_use_bool;
      // Seperate sync
      json_scanf( json_str, json_len,
                  "{video_input_parameters: {seperate_sync: %B}}",
                  &multi_use_bool);
      edid->basic_display_parameters.video_input_parameters
        .analog.seperate_sync = 0x1 & multi_use_bool;
      // Composite sync
      json_scanf( json_str, json_len,
                  "{video_input_parameters: {composite_sync: %B}}",
                  &multi_use_bool);
      edid->basic_display_parameters.video_input_parameters
        .analog.composite_sync = 0x1 & multi_use_bool;
      // Sync on green
      json_scanf( json_str, json_len,
                  "{video_input_parameters: {sync_on_green: %B}}",
                  &multi_use_bool);
      edid->basic_display_parameters.video_input_parameters
        .analog.sync_on_green = 0x1 & multi_use_bool;
      // Vsync serrated
      json_scanf( json_str, json_len,
                  "{video_input_parameters: {blank_to_black: %B}}",
                  &multi_use_bool);
      edid->basic_display_parameters.video_input_parameters
        .analog.blank_to_black = 0x1 & multi_use_bool;
    } else if (strcmp(multi_use_str, "digital") == 0) {
      printf("Digital video configuration is not yet supported.\n");
      return 1;
    } else {
      printf("Error: JSON file format is wrong somewhere around\
              the video input params.\n");
      return 2;
    }
    // %Q mallocs a string
    free(multi_use_str);
    // Horizontal screen size
    json_scanf( json_str, json_len,
                "{video_input_parameters: {horizontal_screen_size: %d}}",
                &multi_use_int);
    edid->basic_display_parameters
      .horizontal_screen_size = multi_use_int;
    // Vertical screen size
    json_scanf( json_str, json_len,
                "{video_input_parameters: {vertical_screen_size: %d}}",
                &multi_use_int);
    edid->basic_display_parameters
      .vertical_screen_size = multi_use_int;
    // Horizontal screen size
    json_scanf( json_str, json_len,
                "{video_input_parameters: {gamma: %f}}",
                &multi_use_flt0);
    edid->basic_display_parameters
      .gamma = (multi_use_flt0-1)*100;
    // Display Power Management Signaling (DPMS)
    // Standby
    json_scanf( json_str, json_len,
                "{video_input_parameters: {features: {dpms: \
                {standby_supported: %B}}}}",
                &multi_use_bool);
    edid->basic_display_parameters
      .features.dpms_standby_supported = 0x1 & multi_use_bool;
    // Suspend
    json_scanf( json_str, json_len,
                "{video_input_parameters: {features: {dpms: \
                {suspend_supported: %B}}}}",
                &multi_use_bool);
    edid->basic_display_parameters
      .features.dpms_suspend_supported = 0x1 & multi_use_bool;
    // Active-off
    json_scanf( json_str, json_len,
                "{video_input_parameters: {features: {dpms: \
                {active_off_supported: %B}}}}",
                &multi_use_bool);
    edid->basic_display_parameters
      .features.dpms_active_off_supported = 0x1 & multi_use_bool;
    // Display type
    char a_str[] = "analog";
    char d_str[] = "digital";
    json_scanf( json_str, json_len,
                "{video_input_parameters: {features: {display_type: %Q}}}",
                &multi_use_str);
    // Create substrings for comparison
    memcpy(a_str, multi_use_str, strlen(a_str));
    memcpy(d_str, multi_use_str, strlen(d_str));
    if (strcmp(a_str, "analog") == 0) {
      // Remove "analog_"
      memcpy( multi_use_str, multi_use_str+strlen(a_str)+1,
              strlen(multi_use_str)-strlen(a_str));
      if (strcmp(multi_use_str, "monochrome_or_grayscale") == 0) {
        edid->basic_display_parameters
          .features.display_type = 0x3 & EDID_DISPLAY_TYPE_MONOCHROME_OR_GRAYSCALE;
      } else if (strcmp(multi_use_str, "rgb_color") == 0) {
        edid->basic_display_parameters
          .features.display_type = 0x3 & ~EDID_DISPLAY_TYPE_RGB_COLOR;
      } else if (strcmp(multi_use_str, "non_rgb_color") == 0) {
        edid->basic_display_parameters
          .features.display_type = 0x3 & ~EDID_DISPLAY_TYPE_NON_RGB_COLOR;
      } else if (strcmp(multi_use_str, "undefined") == 0) {
        edid->basic_display_parameters
          .features.display_type = 0x3 & EDID_DISPLAY_TYPE_UNDEFINED;
      } else {
        printf("Error: Unknown analog display_type.\n");
        return 3;
      }
    } else if (strcmp(d_str, "digital") == 0) {
      printf("Error: Digital format is not supported yet.\n");
      return 4;
    } else {
      printf("Error: JSON format is wrong. First word needs of display_type \
              should either be analog or digital.\n");
    }
    // %Q mallocs a string, which needs to be freed
    free(multi_use_str);
    // Standard sRGB
    json_scanf( json_str, json_len,
                "{video_input_parameters: {features: {standard_srgb: %B}}}",
                &multi_use_bool);
    edid->basic_display_parameters
      .features.standard_srgb = 0x1 & multi_use_bool;
    // Prefered timing mode
    json_scanf( json_str, json_len,
                "{video_input_parameters: {features: {preferred_timing_mode: %B}}}",
                &multi_use_bool);
    edid->basic_display_parameters
      .features.preferred_timing_mode = 0x1 & multi_use_bool;
    // Continuous timings
    json_scanf( json_str, json_len,
                "{video_input_parameters: {features: {continuous_timings: %B}}}",
                &multi_use_bool);
    edid->basic_display_parameters
      .features.continuous_timings = 0x1 & multi_use_bool;
  } else {
    printf("Error: One of either edid or json_str is NULL.\n");
    return 5;
  }
  return 0;
}

int main(void)
{
  //uint8_t edith[EDID_LENGTH];
  edid_t edith;
  memset(&edith, 0x00, sizeof(edith));
  printf("size> %d bytes\n", sizeof(edith));
  generate_preamble(&edith);
  unsigned char* mystr = NULL;
  size_t len = file_to_str(&mystr, "edid_stockach.json");
  if (mystr) {
    printf("%s\n", mystr);
    printf("len> %d\n", len);
    //free(mystr);
  }
  generate_header(&edith, mystr, len);
  generate_basic_display_parameters(&edith, mystr, len);
  disp_buf((uint8_t*)&edith, EDID_LENGTH);
  return 0;
}