allocation related primitives

std/mem/mem.bro

@@ -6,14 +6,51 @@ Allocator :: struct {
 	free @func(context ?*mut anyopaque, memory ?*mut u8, size usize, alignment usize) void
 }
 
-heap Allocator :: Allocator {
+_malloc_alignment usize :: 16 # ponytail: aarch64-macos libc malloc alignment assumption.
+
+_power_of_two func(value usize) bool {
+	if value == 0 {
+		return false
+	}
+
+	current usize = value
+	while current > 1 {
+		half usize = current / 2
+		if half * 2 != current {
+			return false
+		}
+		current = half
+	}
+
+	return true
+}
+
+_c_alloc func(_ ?*mut anyopaque, size usize, alignment usize) ?*mut u8 {
+	if _power_of_two(alignment) == false {
+		return none
+	}
+
+	if alignment <= _malloc_alignment {
+		return ptr_cast(u8, c.malloc(c_ulong(size)))
+	}
+
+	memory [1]mut ?*mut anyopaque = [none]
+	status c_int = c.posix_memalign((&memory).ptr, c_ulong(alignment), c_ulong(size))
+	if status != 0 {
+		return none
+	}
+
+	return ptr_cast(u8, memory[0])
+}
+
+_c_free func(_ ?*mut anyopaque, memory ?*mut u8, _ usize, _ usize) void {
+	c.free(memory)
+}
+
+c_allocator Allocator :: Allocator {
 	context = none,
-	alloc = func(_ ?*mut anyopaque, size usize, _ usize) ?*mut u8 {
-		return ptr_cast(u8, c.malloc(size))
-	},
-	free = func(_ ?*mut anyopaque, memory ?*mut u8, _ usize, _ usize) void {
-		c.free(memory)
-	},
+	alloc = _c_alloc,
+	free = _c_free,
 }
 
 alloc func(allocator Allocator, size usize, alignment usize) ?*mut u8 {