Initial

Commit of begging of port of TheEscape to C

c/Graphics

@@ -0,0 +1,80 @@
+#include <stdio.h>
+#include "swis.h"
+#include <kernel.h>
+
+// SWI Registers
+extern _kernel_swi_regs inreg;
+extern _kernel_swi_regs outreg;
+
+extern unsigned char *buffer;
+
+
+// Loads sprite file into buffer
+void load_sprites(char* filename)
+{
+  int length;
+
+  // Attempt to get file info
+  inreg.r[0] = 13;
+  inreg.r[1] = (int) filename;
+  _kernel_swi(OS_File,&inreg,&outreg);
+
+  // Length will be in R4 if it exists
+  length = outreg.r[4];
+
+  // If it's <1 it's fil not found
+  if(outreg.r[0] < 1)
+  {         
+    printf("Sprite file %s not found",filename);
+    exit(0);
+  }
+
+  // Stops us trying to mallocsomething mad if file is too big.
+  if(length > 200000)
+  {         
+    printf("Sprite file %s seems unreasonably large at %i bytes",filename, length);
+    exit(0);
+  }
+
+  // Attempt malloc, die if we cant
+  buffer = (unsigned char *) malloc(length + 4);
+
+  if(buffer==NULL)
+  {
+    printf("Couldn't malloc %i bytes for sprite buffer",length);
+    exit(0);
+  }
+
+  // Store size and other info as required for SpriteOp 9 to init sprite area
+  *(unsigned int *)buffer = length + 4;
+  *(unsigned int *)(buffer + 4) = 16;
+  inreg.r[0] = 256+9;
+  inreg.r[1] = (unsigned int) buffer;
+  _kernel_swi(OS_SpriteOp,&inreg,&outreg);
+
+  // Load sprite file into buffer
+  inreg.r[0] = 256+10;
+  inreg.r[1] = (int) buffer;
+  inreg.r[2] = (int) filename;
+  _kernel_swi(OS_SpriteOp,&inreg,&outreg);
+}
+
+void display_mode(int mode)
+{
+  // mode 28 80x60 640x480 16 colours
+  inreg.r[0] = 0;
+  inreg.r[1] = mode;
+  _kernel_swi(OS_ScreenMode,&inreg,&outreg);
+}
+
+void draw_sprite(char* spritename,int x, int y)
+{
+  // SpriteOp 34 to put sprite at a location
+  inreg.r[0] = 256+34;
+  inreg.r[1] = (int) buffer;
+  inreg.r[2] = (int) spritename;
+  inreg.r[3] = x;
+  inreg.r[4] = y;
+  inreg.r[5] = 8; // GCOL dest=source and sprite mask
+  _kernel_swi(OS_SpriteOp,&inreg,&outreg);
+}