From 37c257ea6d0270ca3feac75ba1f88b1ce962c663 Mon Sep 17 00:00:00 2001
From: Mike Pavone <pavone@retrodev.com>
Date: Wed, 16 Jan 2013 22:40:56 -0800
Subject: Implement ABCD an SBCD. Fix BTEST with register source.

---
 runtime.S | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

(limited to 'runtime.S')

diff --git a/runtime.S b/runtime.S
index 4024736..88ed7c8 100644
--- a/runtime.S
+++ b/runtime.S
@@ -100,6 +100,64 @@ m68k_invalid:
 	call printf
 	mov $1, %rdi
 	call exit
+
+	.global bcd_add
+bcd_add:
+	xchg %rax, %rdi
+	
+	mov %cl, %ch
+	mov %al, %ah
+	and $0xF, %ch
+	and $0xF, %ah
+	and $0xF0, %cl
+	and $0xF0, %al
+	add %ah, %ch
+	cmp $10, %ch
+	jb no_adjust
+	add $6, %ch
+no_adjust:
+	add %ch, %al
+	add %al, %cl
+	mov $0, %ch
+	jc def_adjust
+	cmp $0xA0, %cl
+	jb no_adjust_h
+def_adjust:
+	add $0x60, %cl
+	mov $1, %ch
+no_adjust_h:
+	
+	mov %rdi, %rax
+	ret
+
+	.global bcd_sub
+bcd_sub:
+	xchg %rax, %rdi
+	
+	mov %cl, %ch
+	mov %al, %ah
+	and $0xF, %ch
+	and $0xF, %ah
+	and $0xF0, %cl
+	and $0xF0, %al
+	sub %ah, %ch
+	cmp $10, %ch
+	jb no_adjusts
+	sub $6, %ch
+no_adjusts:
+	add %ch, %cl
+	sub %al, %cl
+	mov $0, %ch
+	jc def_adjusts
+	cmp $0xA0, %cl
+	jb no_adjust_hs
+def_adjusts:
+	sub $0x60, %cl
+	mov $1, %ch
+no_adjust_hs:
+	
+	mov %rdi, %rax
+	ret
 	
 int_dbg_msg:
 	.asciz "Executing Interrupt!"
-- 
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