From d08c678449574dcd6522f5cd0d4742f966104940 Mon Sep 17 00:00:00 2001
From: jespergravgaard <jesper@balmangravgaard.dk>
Date: Wed, 31 Mar 2021 20:43:36 +0200
Subject: [PATCH] Added a fragment and the start of a line drawing mega65
 program.

---
 src/test/kc/examples/mega65/linedrawing.c | 80 +++++++++++++++++++++++
 1 file changed, 80 insertions(+)
 create mode 100644 src/test/kc/examples/mega65/linedrawing.c

diff --git a/src/test/kc/examples/mega65/linedrawing.c b/src/test/kc/examples/mega65/linedrawing.c
new file mode 100644
index 000000000..f580896d4
--- /dev/null
+++ b/src/test/kc/examples/mega65/linedrawing.c
@@ -0,0 +1,80 @@
+// Test hardware line drawing
+// Based on https://github.com/MEGA65/mega65-tools/blob/master/src/tests/test_290.c
+
+#pragma target(mega65)
+#include <mega65.h>
+#include <6502.h>
+
+#define POKE(addr,val) *((char*)(addr)) = val
+
+// Poke a value directly into memory
+// - addr: The 32bit address to poke to
+// - val: The value to poke
+void lpoke(__zp unsigned long addr, char val) {
+    // Use the 45GS02 32-bit addressing mode
+    asm {
+        ldz #0
+        lda val
+        sta ((addr)),z
+    }
+}
+
+void main() {
+
+    // Avoid interrupts
+    SEI();
+    // Map memory to BANK 0 : 0x00XXXX - giving access to I/O
+    memoryRemap(0,0,0);
+
+    // Fast CPU, M65 IO
+    POKE(0, 65);
+    POKE(0xD02F, 0x47);
+    POKE(0xD02F, 0x53);    
+  
+    graphics_mode();
+
+    for(;;) ;
+
+
+}
+
+
+void graphics_mode(void) {
+
+  // 16-bit text mode, full-colour text for high chars
+  POKE(0xD054, 0x05);
+  // H320, fast CPU
+  POKE(0xD031, 0x40);
+  // 320x200 per char, 16 pixels wide per char
+  // = 320/8 x 16 bits = 80 bytes per row
+  POKE(0xD058, 80);
+  POKE(0xD059, 80 / 256);
+  // Draw 40 chars per row
+  POKE(0xD05E, 40);
+  
+  // Put 2KB screen at $C000
+  POKE(0xD060, 0x00);
+  POKE(0xD061, 0xc0);
+  POKE(0xD062, 0x00);
+ 
+  // Layout screen so that graphics data comes from $40000 -- $4FFFF
+  unsigned int i = 0x40000 / 0x40;
+  for (unsigned int a = 0; a < 40; a++)
+    for (unsigned int b = 0; b < 25; b++) {
+      POKE(0xC000 + b * 80 + a * 2 + 0, (char)(i & 0xff));
+      POKE(0xC000 + b * 80 + a * 2 + 1, (char)(i >> 8));
+      i++;
+    }
+
+  // Clear colour RAM
+  for (unsigned int i = 0; i < 2000; i++) {
+    lpoke(0xff80000l + 0 + i, 0x00);
+    lpoke(0xff80000l + 1 + i, 0x00);
+  }
+
+  // Black border and background
+  POKE(0xD020, 0);
+  POKE(0xD021, 0);
+
+}
+