bulk data dump

initial commit

README.md

@@ -1 +1,4 @@
-# playfield
+This is a conversion of a piece of code from the Amiga Hardware Reference Manual - Second Printing - July 1986 (page 55)
+under the heading "examples of forming basic playfields"
+Essentially it is a translation of Motorola 68000 assembly to C language code, utilising SDL2 obviously instead of banging the metal directly to display the output.
+

playfield.c

@@ -0,0 +1,121 @@
+/********************************************************
+ ** FILENAME   : playfield.c                           **
+ ** AUTHOR     : Jason Bou-Samra                       **
+ **            : Paragon                               **
+ ** DATE       : 09/01/2023                            **
+ ** DESCRIPTION: amiga 1000 playfield example          **
+ ** NOTES      : a recreation of the amiga 1000        **
+ **              playfield example in C/SDL            **
+ ** CHANGES    : see changes.txt                       **
+ ********************************************************/
+/* to compile: cc name.c -lSDL2 -lm */
+
+#include <stdio.h>
+#include <SDL2/SDL.h>
+#include <math.h>
+#include <stdbool.h>
+
+int initSDL (void);
+int shutdownSDL (void);
+int do_playfield(void);
+
+bool quit = false;                  /* quit flag */
+
+SDL_Window *window = NULL;
+SDL_Renderer *sr;
+SDL_Event event;
+
+int p1x, p2x, line;
+
+/* window paramaters */
+#define WIDTH 640					/* pixels */
+#define HEIGHT 512					/* pixels */
+#define TITLE "Playfield Example"	/* window title */
+
+int main (void)
+{
+  initSDL ();
+  SDL_RenderSetScale (sr, 2.0, 2.0);			/* scale x2 */
+
+  while (quit == false)
+    {
+
+      while (SDL_PollEvent (&event))
+	{
+	  if (event.type == SDL_QUIT || event.type == SDL_WINDOWEVENT_CLOSE)
+	    {
+	      quit = true;
+	    }
+	}
+      if (quit)
+	{
+	  break;
+	}
+
+do_playfield();
+
+ SDL_Delay(50);
+    }
+  shutdownSDL ();					/* bye */
+}
+
+/* initialise SDL */
+int initSDL ()
+{
+  SDL_Init (SDL_INIT_EVERYTHING);
+
+/* new window */
+  window = SDL_CreateWindow (TITLE,			/* title */
+			     SDL_WINDOWPOS_UNDEFINED,	/* x pos */
+			     SDL_WINDOWPOS_UNDEFINED,	/* w pos */
+			     WIDTH,			/* width */
+			     HEIGHT,			/* height */
+			     0);			/* Additional flag(s) */
+
+  /* deal with error */
+  if (window == NULL)
+    {
+      fprintf (stderr, "SDL window failed to initialise: %s\n",
+	       SDL_GetError ());
+      return 1;
+    }
+
+/* creater renderer */
+  sr = SDL_CreateRenderer (window, 0, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
+}
+
+/* shutdown routine */
+int shutdownSDL ()
+{
+  SDL_DestroyWindow (window);				/* free memory */
+  SDL_Quit ();						/* shutdown entire sdl sub-systems */
+  return 0;
+}
+
+int do_playfield()
+{
+  SDL_SetRenderDrawColor (sr, 0xFF, 0x00, 0x00, 0xFF); /* background */
+  SDL_RenderClear (sr); 
+  SDL_SetRenderDrawColor (sr, 0xFF, 0xFF, 0x00, 0xFF); /* set pen colour*/
+
+line=0;
+  for (int i=0; i<200; i++)  // 200 lines
+{
+  p1x=0; p2x=7;
+
+for (int j=0; j<20; j++) // #FF00FF00 recreate pattern
+{
+  SDL_RenderDrawLine (sr, p1x, line, p2x, line);
+
+      p2x=p2x+16;
+      p1x=p1x+16;
+//      printf("%i %i %i\n", line, p1x, p2x);
+}
+  line=line+1;
+  }
+    SDL_RenderPresent (sr);
+}
+
+/* author*/
+char author[] = { "amiga 1000 playfield example" };
+const char* text = "by commodore amiga inc.";