From e4473e14f640a104dffeb52cabbe90b4722848f5 Mon Sep 17 00:00:00 2001
From: Paul Mathieu <paul@ponteilla.net>
Date: Wed, 24 Sep 2025 00:45:32 +0200
Subject: [PATCH] make crc16.s

---
 crc16.s | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 crc16.s

diff --git a/crc16.s b/crc16.s
new file mode 100644
index 0000000..000465d
--- /dev/null
+++ b/crc16.s
@@ -0,0 +1,52 @@
+	.arch i8086,jumps
+	.code16
+	.att_syntax prefix
+#NO_APP
+#APP
+	.global main      
+main:             
+  push %bp        
+  mov %sp, %bp    
+  mov 8(%bp), %si 
+  push (%si)      
+  call crc16      
+  add $0x2, %sp   
+  mov 6(%bp), %di 
+  mov %ax, (%di)  
+  pop %bp         
+  lret $4         
+
+#NO_APP
+	.text
+	.global	crc16
+	.type	crc16, @function
+crc16:
+	pushw	%bp
+	movw	%sp,	%bp
+	xorw	%bx,	%bx
+	movw	$-1,	%ax
+.L2:
+	cmpw	4(%bp),	%bx
+	jne	.L5
+	popw	%bp
+	ret
+.L5:
+	movb	(%bx),	%dl
+	movb	$8,	%cl
+	shlw	%cl,	%dx
+	xorw	%dx,	%ax
+	movb	%cl,	%dl
+.L4:
+	movw	%ax,	%cx
+	shlw	$1,	%cx
+	testw	%ax,	%ax
+	xchgw	%ax,	%cx
+	jge	.L3
+	xorw	$4129,	%ax
+.L3:
+	decb	%dl
+	jne	.L4
+	incw	%bx
+	jmp	.L2
+	.size	crc16, .-crc16
+	.ident	"GCC: (GNU) 6.3.0"