1 files changed, 57 insertions, 0 deletions
diff --git a/zap/src/mem/streq.S b/zap/src/mem/streq.S
new file mode 100644
index 0000000..d331e93
--- /dev/null
+++ b/zap/src/mem/streq.S
@@ -0,0 +1,57 @@
+/*
+	Copyright 2022 Gabriel Jensen.
+	This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
+	If a copy of the MPL was not distributed with this file, You can obtain one at https://mozilla.org/MPL/2.0/.
+*/
+
+#include <zap/priv.h>
+
+.globl zap_streq
+
+zap_streq:
+
+	/*
+		char const * lstr
+		char const * rstr
+	*/
+
+#if defined(__amd64__)
+
+	# rdi: Address of the current left character.
+	# rsi: Address of the current right character.
+	# rax: Current left character.
+	# rdx: Current right character.
+
+	# Iterate over the strings:
+.loop:
+
+	# Copy the characters into registers:
+	movb (%rdi),%al
+	movb (%rsi),%dl
+
+	# Check if the characters are equal:
+	cmpb %al,%dl
+	jne .neq # If not, the strings also aren't equal.
+
+	# Check if we have reached the null-terminator:
+	testb %al,%al
+	jz .eq # If so, all previous characters have compared equal, and the strings are equal.
+
+	# Continue to the next characters:
+	incq %rdi
+	incq %rsi
+	jmp .loop
+
+	# The strings have compared equal:
+.eq:
+
+	movb $0xFF,%al
+	ret
+
+	/* The strings have compared unequal: */
+.neq:
+
+	movb $0x0,%al
+	ret
+
+#endif