1 files changed, 39 insertions, 0 deletions
diff --git a/zap/source/amd64/mem/strcp.S b/zap/source/amd64/mem/strcp.S
new file mode 100644
index 0000000..eb5c276
--- /dev/null
+++ b/zap/source/amd64/mem/strcp.S
@@ -0,0 +1,39 @@
+# 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_strcp
+
+zap_strcp:
+	# rax: Address of the current input character.
+	# rdi: Address of the first input character.
+	# rsi: Address of the current output character.
+	# rdx: Current character.
+
+	movq %rdi,%rax
+
+	# Iterate over the strings:
+.loop:
+
+	# Copy character:
+	movb (%rax),%dl # Move it into a register...
+	movb %dl,(%rsi) # ... and then back into memory.
+
+	# Check if we have reached the null-terminator:
+	testb %dl,%dl
+	jz .done
+
+	# Continue to the next character:
+
+	incq %rax
+	incq %rsi
+	jmp .loop
+
+	# Finish:
+.done:
+
+	# Get the length of the (input) string:
+	subq %rdi,%rax
+	decq %rax # We do not count the null-terminator in the string length.
+
+	ret