ilda-display.c

#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>

#include <SDL2/SDL.h>

#include "ilda-decoder.h"

#define STRICT_MODE 0x8000

static ssize_t read_file(void *opaque, void *buffer, size_t len) {
  ssize_t r = read((int)(long)opaque & ~STRICT_MODE, buffer, len);
  if (r == 0) {
    if ((int)(long)opaque & STRICT_MODE) {
      fprintf(stderr, "end of file encountered before ILDA end marker\n");
      exit(1);
    }
    lseek((int)(long)opaque, 0, SEEK_SET);
    r = read((int)(long)opaque, buffer, len);
  }
  return r;
}

#define DIM 600

int transform(int x) { return (x + 32768) * 599 / 65535; }

int main(int argc, char *argv[]) {
  if (argc != 2) {
    fprintf(stderr, "Usage: ilda-display FILE\n");
    fprintf(stderr, "  Press space bar to pause and Q to quit\n");
    fprintf(
        stderr,
        "  Use strict mode if ILDA_STRICT_MODE environment variable exists\n");
    exit(1);
  }
  int f = open(argv[1], 0);
  if (f < 0) {
    perror("cannot open file");
    exit(1);
  }
  if (SDL_Init(SDL_INIT_VIDEO) < 0) {
    fprintf(stderr, "cannot initialize SDL\n");
    exit(1);
  }
  SDL_Window *window =
      SDL_CreateWindow("ILDA display", SDL_WINDOWPOS_CENTERED,
                       SDL_WINDOWPOS_CENTERED, DIM, DIM, SDL_WINDOW_SHOWN);
  if (!window) {
    fprintf(stderr, "cannot create SDL window\n");
    exit(1);
  }
  SDL_Renderer *renderer = SDL_CreateRenderer(window, -1, 0);
  int pause = 0;
  ilda_state_t ilda;
  int strict_mode = getenv("ILDA_STRICT_MODE") == NULL ? 0 : STRICT_MODE;
  ilda_init(&ilda, read_file, (void *)((long)f | strict_mode), strict_mode);
  ilda_pos_t last_point = {0, 0, 0};
  for (;;) {
    SDL_Event event;
    while (SDL_PollEvent(&event)) {
      if (event.type == SDL_QUIT ||
          (event.type == SDL_KEYDOWN && event.key.keysym.sym == SDLK_q))
        goto bye;
      if (event.type == SDL_KEYDOWN && event.key.keysym.sym == SDLK_SPACE)
        pause ^= 1;
    }
    if (pause) {
      SDL_Delay(40);
      continue;
    }
    const ilda_header_t *header = ilda_read_next_header(&ilda);
    if (header == NULL) {
      fprintf(stderr, "error when reading ILDA file: %s\n", ilda.error);
      exit(1);
    }
    if (ilda_is_end_of_file(header)) {
      lseek(f, 0, SEEK_SET);
      continue;
    }
    if (ilda_is_palette(header)) {
      if (ilda_read_palette(&ilda)) {
        fprintf(stderr, "error when reading palette: %s\n", ilda.error);
        exit(1);
      }
    } else {
      static ilda_point_t buffer[65536];
      if (ilda_read_records(&ilda, buffer, sizeof buffer)) {
        fprintf(stderr, "error when reading records: %s\n", ilda.error);
        exit(1);
      }
      SDL_SetRenderDrawColor(renderer, 0, 0, 0, SDL_ALPHA_OPAQUE);
      SDL_RenderClear(renderer);
      for (size_t i = 0; i < header->number_of_records; i++) {
        const ilda_point_t *point = &buffer[i];
        if (!ilda_is_blanking(point->status_code)) {
          SDL_SetRenderDrawColor(renderer, point->color.r, point->color.g,
                                 point->color.b, SDL_ALPHA_OPAQUE);
          SDL_RenderDrawLine(
              renderer, transform(last_point.x), DIM - transform(last_point.y),
              transform(point->pos.x), DIM - transform(point->pos.y));
        }
        memcpy(&last_point, point, sizeof last_point);
      }
      SDL_RenderPresent(renderer);
      SDL_Delay(40);
    }
  }

bye:
  SDL_DestroyRenderer(renderer);
  SDL_DestroyWindow(window);
  SDL_Quit();
}