From 8998bd04c94da08dc49ab62007da5604d53895c3 Mon Sep 17 00:00:00 2001
From: "Juan J. Martinez" <jjm@usebox.net>
Date: Mon, 1 May 2023 13:50:52 +0100
Subject: Initial import

---
 example.asm | 125 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 125 insertions(+)
 create mode 100644 example.asm

(limited to 'example.asm')

diff --git a/example.asm b/example.asm
new file mode 100644
index 0000000..6d4521e
--- /dev/null
+++ b/example.asm
@@ -0,0 +1,125 @@
+;
+; example.asm for TR8
+;
+.org 0
+
+;     ; copy 16K from 0x0000 to 0xbf00
+;     ;
+; start:
+;     ld a, 0
+;     ld b, 0xbf
+;     ld x, 0
+;     ld y, 0x40
+; loop:
+;     push y
+;     ld y, [a : x]
+;     ld [b : x], y
+;     pop y
+;     inc x
+;     bno
+;     jmp loop
+;     inc a
+;     inc b
+;     dec y
+;     bnz
+;     jmp loop
+;
+    ld b, 15
+    call fill
+
+    halt
+;
+;     ; void copy(void *dst, void *src, uint16_t size)
+;     ; size = 0x1000
+;     ; src = 0
+;     ; dst 0xbf00
+;     ld a, 0x10
+;     push a
+;     ld a, 0
+;     push a
+;     push a
+;     push a
+;     ld a, 0xbf
+;     push a
+;     ld a, 0
+;     push a
+;     call copy
+;     pop a
+;     pop a
+;     pop a
+;     pop a
+;     pop a
+;     pop a
+;     halt
+
+    ; fill frame-buffer with a color in reg b
+fill:
+    ld a, 0xbf
+    ld x, 0
+    ld y, 0x40
+fill_loop:
+    ld [a : x], b
+    inc x
+    bno
+    jmp fill_loop
+    inc a
+    dec y
+    bnz
+    jmp fill_loop
+    ret
+
+    ; void copy(void *dst, void *src, uint16_t size)
+    ;
+    ; using C calling convention with the stack
+    ; not used, but return value in a (8-bit), a: x (16-bit)
+; copy:
+;     ld x, [sp + 6]
+;     ld a, [sp + 7] ; size a:x
+;
+;     ; local variable
+;     push a
+;     push x
+;
+;     ld y, [sp + 4]
+;     ld b, [sp + 5] ; dst b:y
+;     ld x, [sp + 6]
+;     ld a, [sp + 7] ; src a:x
+; copy_loop:
+;     ; copy byte from a:x to b:y
+;     push x
+;     ld x, [a : x]
+;     ld [b : y], x
+;     pop x
+;
+;     ; inc a:x
+;     inc x
+;     bo
+;     inc a
+;
+;     ; inc b:y
+;     inc y
+;     bo
+;     inc b
+;
+;     ; dec local var size
+;     push a
+;     push x
+;     ld x, [sp + 2]
+;     ld a, [sp + 3]
+;     dec x
+;     bo
+;     dec a
+;     ld [sp + 2], x
+;     ld [sp + 3], a
+;     or x, a
+;     pop x
+;     pop a
+;
+;     bnz
+;     jmp copy_loop
+;
+;     pop x
+;     pop x ; free local var
+;     ret
+;
+;
-- 
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