1 files changed, 45 insertions, 0 deletions
diff --git a/zap/src/mem/memfill.S b/zap/src/mem/memfill.S
new file mode 100644
index 0000000..63a1aad
--- /dev/null
+++ b/zap/src/mem/memfill.S
@@ -0,0 +1,45 @@
+/*
+	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_memfill
+
+zap_memfill:
+
+	/*
+		void const *  ptr
+		zap_sz        num
+		unsigned char val
+	*/
+
+#if defined(__amd64__)
+
+	# rdi: Address of the current element.
+	# rsi: Address of the element after the last element.
+	# rdx: Byte value.
+
+	addq %rdi,%rsi
+
+	# Iterate over buffer:
+.loop:
+
+	# Check if we have reached the final element:
+	cmpq %rdi,%rsi
+	je .done # Exit loop if we have.
+
+	# Set the value of the current element:
+	movb %dl,(%rdi)
+
+	# Continue to next element:
+	incq %rdi
+	jmp .loop
+
+	# Finish:
+.done:
+	ret
+
+#endif