Remove `mem_zero` from `make`; Implement custom `memset` for windows amd64

core/runtime/core.odin

@@ -631,7 +631,7 @@ make_aligned :: proc($T: typeid/[]$E, auto_cast len: int, alignment: int, alloca
 	if data == nil && size_of(E) != 0 {
 		return nil;
 	}
-	mem_zero(data, size_of(E)*len);
+	// mem_zero(data, size_of(E)*len);
 	s := Raw_Slice{data, len};
 	return transmute(T)s;
 }
@@ -659,7 +659,7 @@ make_dynamic_array_len_cap :: proc($T: typeid/[dynamic]$E, auto_cast len: int, a
 	if data == nil && size_of(E) != 0 {
 		s.len, s.cap = 0, 0;
 	}
-	mem_zero(data, size_of(E)*cap);
+	// mem_zero(data, size_of(E)*cap);
 	return transmute(T)s;
 }
 

core/runtime/procs_windows_amd64.odin

@@ -30,10 +30,14 @@ memmove :: proc "c" (dst, src: rawptr, len: int) -> rawptr {
 
 // @(link_name="memset")
 memset :: proc "c" (ptr: rawptr, val: i32, len: int) -> rawptr {
-	foreign kernel32 {
-		RtlFillMemory :: proc "c" (dst: rawptr, len: int, fill: byte) ---
+	b := byte(val);
+
+	p_start := uintptr(ptr);
+	p_end := p_start + uintptr(max(len, 0));
+	for p := p_start; p < p_end; p += 1 {
+		(^byte)(p)^ = b;
 	}
-	RtlFillMemory(ptr, len, byte(val));
+
 	return ptr;
 }