From 3901d8ea71d32282333330feaa36ac10d3f5e375 Mon Sep 17 00:00:00 2001
From: Martin Perner <martin@perner.cc>
Date: Wed, 27 Oct 2010 17:04:35 +0200
Subject: [PATCH] isa: stefans sample

---
 2_isa/src/palindrom.c | 19 +++++++++++++++++++
 2_isa/src/palindrom.s | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+)
 create mode 100755 2_isa/src/palindrom.c
 create mode 100755 2_isa/src/palindrom.s

diff --git a/2_isa/src/palindrom.c b/2_isa/src/palindrom.c
new file mode 100755
index 0000000..e065673
--- /dev/null
+++ b/2_isa/src/palindrom.c
@@ -0,0 +1,19 @@
+/* palindrom checker */
+
+u8 palindrom(u8* str, u8 len) {
+	u8 *str1, *str2;
+	if (len == 0) { 
+		return 0;
+	}
+	str1 = str; 
+	str2 = str + len - 1;
+
+	while (str1 < str2) {
+		if (*str1 != *str2) { 
+			return 0;
+		}
+		str1++;
+		str2--;
+	}
+	return 1;
+}
diff --git a/2_isa/src/palindrom.s b/2_isa/src/palindrom.s
new file mode 100755
index 0000000..8094db3
--- /dev/null
+++ b/2_isa/src/palindrom.s
@@ -0,0 +1,35 @@
+; palindrom checker
+
+; r1 = str addr
+; r2 = str len (u8)
+
+	ldi r0, 0
+
+	cmp r1, 0
+	retzs		; return 0 if strlen = 0
+
+	add  r4, r1, r2 ; set r4 to end address
+	subi r4, 1
+
+	cmp  r1, r4	; if strlen = 1 return 1
+	brancheq- end
+
+schleife:
+
+	ldb  r5, r1
+	ldb  r6, r4
+
+	cmp  r5, r6
+	retnq		; return 0 when palindrom not satisfied
+
+	addi r1, r1, 1
+	subi r4, r4, 1
+
+	cmp  r1, r4
+
+	branchlt+ schleife
+
+end:
+
+	ldi  r0, 1
+	ret
-- 
2.25.1