drm_fourcc

#!/usr/bin/env bash
set -eu -o pipefail

declare -r drm_fourcc_h=/usr/include/libdrm/drm_fourcc.h
declare -r prog="${BASH_SOURCE[0]}".out

update() {
  fourcc_h=$(perl -pe 's/\\\n//' < "$drm_fourcc_h")
  fourcc_code=($(echo "$fourcc_h" | grep -E '#define\s+\w+\s+fourcc_code' | awk '{print $2}'))
  fourcc_mod_code=($(echo "$fourcc_h" | grep -E '#define\s+\w+\s+fourcc_mod_code' | awk '{print $2}'))

  c=$(mktemp --suffix=.c)
  cat >> "$c" <<'EOF'
#include <ctype.h>
#include <errno.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <drm_fourcc.h>
EOF

  cat >> "$c" <<'EOF'
static void
drm_print(const char* const name, const uint64_t value)
{
  printf("%s = %lu (%#lx)\n", name, value, value);
}
EOF

  cat >> "$c" <<'EOF'
static bool
number_from_name(const char * const name)
{
#define CASE(x) \
  if (strcmp(#x, name) == 0) \
  { \
    drm_print(name, x); \
    return true; \
  }
EOF
  printf '  CASE(%s);\n' >> "$c" "${fourcc_code[@]}"
  printf '  CASE(%s);\n' >> "$c" "${fourcc_mod_code[@]}"
  cat >> "$c" <<'EOF'
#undef CASE
  return false;
}
EOF

  cat >> "$c" <<'EOF'
static bool
format_name_from_number(const uint32_t number)
{
  bool found = false;
#define CASE(x) do { \
  if (number == x) { \
    drm_print(#x, x); \
    found = true; \
  } \
} while(0)
EOF

  printf '    CASE(%s);\n' >> "$c" "${fourcc_code[@]}"

  cat >> "$c" <<'EOF'
#undef CASE
  return found;
}
EOF

  cat >> "$c" <<'EOF'
static bool
modifier_name_from_number(const uint64_t number)
{
  bool found = false;
#define CASE(x) do { \
  if (number == x) { \
    drm_print(#x, x); \
    found = true; \
  } \
} while(0)
EOF

  printf '    CASE(%s);\n' >> "$c" "${fourcc_mod_code[@]}"

  cat >> "$c" <<'EOF'
#undef CASE
  return found;
}
EOF

  cat >> "$c" <<'EOF'
static void
list_all_names()
{
#define CASE(x) do { \
  printf("- "); \
  drm_print(#x, x); \
} while(0)
EOF

  printf '  printf("Known DRM formats:\\n");\n' >> "$c"
  printf '  CASE(%s);\n' >> "$c" "${fourcc_code[@]}"
  printf '  printf("\\n");\n' >> "$c"
  printf '  printf("Known DRM modifiers:\\n");\n' >> "$c"
  printf '  CASE(%s);\n' >> "$c" "${fourcc_mod_code[@]}"

  cat >> "$c" <<'EOF'
#undef CASE
}
EOF


  cat >> "$c" <<'EOF'
int main(int argc, char* argv[])
{
  if (argc < 2) {
    list_all_names();
    return 0;
  }

  for (int i = 1; i < argc; i++)
  {
    if (isdigit(argv[i][0]))
    {
      errno = 0;
      char *end;
      uint64_t number = strtoull(argv[i], &end, 0);
      if (errno != 0 || end == argv[i] || *end != '\0') {
        printf("unreadable number: %s\n", argv[i]);
        continue;
      }
      if (!format_name_from_number(number) &&
          !modifier_name_from_number(number))
        printf("unknown number: %s\n", argv[i]);
    }
    else
    {
      if (!number_from_name(argv[i]))
        printf("unknown name: %s\n", argv[i]);
    }
  }
  return 0;
}
EOF

  cc $(pkg-config --cflags --libs libdrm) -o "$prog" "$c" -Wall -Wextra || {
    cat "$c"
    rm "$c"
    exit 1
  }
  rm "$c"
}

if [ ! -f "$prog" ] ||
   [ $(stat -c %Y "$prog") -lt $(stat -c %Y "$drm_fourcc_h") ] ||
   [ $(stat -c %Y "$prog") -lt $(stat -c %Y "${BASH_SOURCE[0]}") ]
then
  update
fi

exec "$prog" "$@"