1 files changed, 58 insertions, 0 deletions
diff --git a/zap/src/memfill.c b/zap/src/memfill.c
new file mode 100644
index 0000000..70982c4
--- /dev/null
+++ b/zap/src/memfill.c
@@ -0,0 +1,58 @@
+/*
+ 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>
+#include <stdint.h>
+
+#if defined(zap_priv_fastimpl)
+__asm__ (
+ ".global zap_memfill\n"
+
+ "zap_memfill:\n"
+ /*
+ void const * ptr
+ size_t num
+ uint_least8_t val
+ */
+#if defined(sus_arch_amd64)
+ /* rdi: Address of the current element. */
+ /* rsi: Address of the element after the last element. */
+ "addq %rdi,%rsi\n"
+ ".loop:\n"
+ "cmpq %rsi,%rdi\n"
+ "je .done\n" /* Exit loop if we have reached the final element. */
+ "movb %dl,(%rdi)\n"
+ "incq %rdi\n"
+ "jmp .loop\n" /* Continue to next element. */
+ ".done:\n"
+ "ret\n"
+#elif defined(sus_arch_ia32)
+ /* eax: Address of the current element. */
+ "movl 0x4(%esp),%eax\n"
+ /* ecx: Address of the element after the last element. */
+ "movl 0x4(%esp),%ecx\n"
+ "addl 0x8(%esp),%ecx\n"
+ /* edx: Byte value. */
+ "movb 0xC(%esp),%dl\n"
+ ".loop:\n"
+ "cmpl %eax,%ecx\n"
+ "je .done\n" /* Exit loop if we have reached the final element. */
+ "movb %dl,(%eax)\n"
+ "incl %eax\n"
+ "jmp .loop\n" /* Continue to next element. */
+ ".done:\n"
+ "ret\n"
+#endif
+);
+#else
+void zap_memfill(void * const _ptr,size_t const _num,uint_least8_t const _byte) {
+ uint_least8_t * pos = (uint_least8_t *)_ptr;
+ uint_least8_t * const afterbuf = pos + _num;
+ for (;pos != afterbuf;++pos) {*pos = _byte;}
+}
+#endif