1 files changed, 69 insertions, 0 deletions
diff --git a/zap/src/strcpy.c b/zap/src/strcpy.c
new file mode 100644
index 0000000..3dc3e0f
--- /dev/null
+++ b/zap/src/strcpy.c
@@ -0,0 +1,69 @@
+/*
+ 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>
+
+#include <stddef.h>
+
+#if defined(zap_priv_fastimpl)
+__asm__ (
+ ".global zap_strcpy\n"
+
+ "zap_strcpy:\n"
+ /*
+ char const * in
+ char const * out
+ */
+#if defined(sus_arch_amd64)
+ /* rax: Address of the current input character. */
+ "movq %rdi,%rax\n"
+ /* rsi: Address of the current output character. */
+ "movq %rsi,%rsi\n"
+ /* rdx: Current character. */
+ ".loop:\n"
+ "movb (%rax),%dl\n" /* Move current the character into a register... */
+ "movb %dl,(%rsi)\n" /* ... and then back into memory. */
+ "testb %dl,%dl\n" /* Check if we have reached the null-terminator... */
+ "jz .done\n" /* ... and if so, we are finished copying. */
+ "incq %rax\n" /* Increment the positions. */
+ "incq %rsi\n"
+ "jmp .loop\n" /* Restart the loop. */
+ ".done:\n"
+ "subq %rdi,%rax\n" /* Get the length of the string we copyied. */
+ "decq %rdi\n" /* We do not count the null-terminator in the string length. */
+ "ret\n"
+#elif defined(sus_arch_ia32)
+ /* eax: Address of the current input character. */
+ "movl 0x4(%esp),%eax\n"
+ /* ecx: Address of the current output character. */
+ "movl 0x8(%esp),%ecx\n"
+ /* edx: Current character. */
+ ".loop:\n"
+ "movb (%eax),%dl\n" /* Move current the character into a register... */
+ "movb %dl,(%ecx)\n" /* ... and then back into memory. */
+ "testb %dl,%dl\n" /* Check if we have reached the null-terminator... */
+ "jz .done\n" /* ... and if so, we are finished copying. */
+ "incl %eax\n" /* Increment the positions. */
+ "incl %ecx\n"
+ "jmp .loop\n" /* Restart the loop. */
+ ".done:\n"
+ "subl 0x4(%esp),%eax\n" /* Get the length of the string we copyied. */
+ "decl %ecx \n" /* We do not count the null-terminator in the string length. */
+ "ret\n"
+#endif
+);
+#else
+size_t zap_strcpy(char const * const _in,char * const _out) {
+ char const * inpos = _in;
+ char * outpos = _out;
+ for (;;++inpos,++outpos) {
+ char const chr = *inpos;
+ *outpos = chr;
+ if (chr == '\x0') {return (size_t)(inpos - _in);}
+ }
+ sus_unreach();
+}
+#endif