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