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