1 files changed, 34 insertions, 0 deletions
diff --git a/zap/source/amd64/mem/strfill.S b/zap/source/amd64/mem/strfill.S
new file mode 100644
index 0000000..590b99f
--- /dev/null
+++ b/zap/source/amd64/mem/strfill.S
@@ -0,0 +1,34 @@
+# 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/.
+
+.globl zap_strfill
+
+zap_strfill:
+	# rdi: Address of the first character of the string.
+	# rsi: Fill character.
+	# rax: Address of the current character.
+
+	movq %rdi,%rax
+
+	# Iterate over string:
+.loop:
+
+	# Check if we have reached the null-terminator:
+	cmpb $0x0,(%rax)
+	je .done # Exit loop if we have.
+
+	# Set the value of the current element:
+	movb %sil,(%rax)
+
+	# Continue to next character:
+	incq %rax
+	jmp .loop
+
+	# Finish:
+.done:
+
+	# Get the length of the string:
+	subq %rdi,%rax
+
+	ret