Add code and binary

README.md

@@ -1,2 +1,28 @@
-# amiga-allocmem-example-code
-The C program used in "What the Heck is NoFastMem?" to show how AllocMem works
+# Amiga AllocMem Example Code
+
+The C program used in "What the Heck is NoFastMem?" to show how AllocMem works.
+View the video here: https://www.youtube.com/watch?v=CDUtoaqKkkk
+
+## Compiling
+
+You'll need [vbcc](http://sun.hasenbraten.de/vbcc/) with the m68k target and the appropriate Native
+Development Kit headers installed:
+
+```
+vc -lauto -lamiga -c99 +kick13 -o mem mem.c
+```
+
+`mem` included in this repo is built with the above command and
+should run on AmigaOS 1.3 and higher.
+
+## Running
+
+Open a Shell on an Amiga with Fast RAM and run:
+
+```
+mem
+run nofastmem
+mem
+run nofastmem
+run
+```

mem.c

@@ -0,0 +1,57 @@
+#include <proto/exec.h>
+#include <proto/dos.h>
+#include <exec/exec.h>
+#include <clib/exec_protos.h>
+#include <clib/graphics_protos.h>
+
+#include <hardware/dmabits.h>
+#include <hardware/custom.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define MEMORY_SIZE (100)
+
+extern struct Custom custom;
+
+UBYTE *buffer;
+UBYTE *target;
+
+void cleanUp() {
+  if (buffer) FreeMem(buffer, MEMORY_SIZE);
+  if (target) FreeMem(target, MEMORY_SIZE);
+}
+
+int main() {
+  atexit(cleanUp);
+
+  buffer = AllocMem(MEMORY_SIZE, MEMF_CLEAR);
+  target = AllocMem(MEMORY_SIZE, MEMF_CLEAR);
+
+  strcpy((char*)buffer, "Agnus copied me since I am in Chip RAM. Thanks, Agnus!");
+  strcpy((char*)target, "Oh no, the blitter can't work with me since I'm in Fast RAM (or Slow RAM).");
+
+  // Agnus blitter stuff
+  OwnBlitter(); WaitBlit(); // Wait for the blitter to finish up its current operation.
+  custom.bltcon0 = 0x09f0;
+  custom.bltcon1 = 0;
+  custom.bltapt = buffer;
+  custom.bltdpt = target;
+  custom.bltamod = 0;
+  custom.bltdmod = 0;
+  custom.bltafwm = 0xffff;
+  custom.bltalwm = 0xffff;
+  // Setting bltsize starts the blitter operation
+  custom.bltsize = (1 * 64) + (MEMORY_SIZE / 2); // 1 "row", convert byte width to words
+  DisownBlitter(); WaitBlit(); // Wait before we do anything else with the Chip RAM we (might) have.
+    
+  printf("\n%s\n\n", target);
+
+  if (buffer) FreeMem(buffer, MEMORY_SIZE);
+  if (target) FreeMem(target, MEMORY_SIZE);
+
+  buffer = 0;
+  target = 0;
+}
+