Separate out the virtual memory allocation procedures

`reserve`, `commit`, `reserve_and_commit`, `decommit`, `release`, `protect`

core/mem/virtual/arena.odin

@@ -12,9 +12,8 @@ Growing_Arena :: struct {
 }
 
 DEFAULT_MINIMUM_BLOCK_SIZE :: 1024*1024 // 1 KiB should be enough
-DEFAULT_PAGE_SIZE := 4096
 
-growing_arena_alloc :: proc(arena: ^Growing_Arena, min_size: int, alignment: int) -> (data: []byte, err: mem.Allocator_Error) {
+growing_arena_alloc :: proc(arena: ^Growing_Arena, min_size: int, alignment: int) -> (data: []byte, err: Allocator_Error) {
 	align_forward_offset :: proc(arena: ^Growing_Arena, alignment: int) -> int #no_bounds_check {
 		alignment_offset := 0
 		ptr := uintptr(arena.curr_block.base[arena.curr_block.used:])
@@ -71,7 +70,7 @@ growing_arena_free_all :: proc(arena: ^Growing_Arena) {
 	arena.total_used = 0
 }
 
-growing_arena_bootstrap_new_by_offset :: proc($T: typeid, offset_to_arena: uintptr, minimum_block_size := DEFAULT_MINIMUM_BLOCK_SIZE) -> (ptr: ^T, err: mem.Allocator_Error) {
+growing_arena_bootstrap_new_by_offset :: proc($T: typeid, offset_to_arena: uintptr, minimum_block_size := DEFAULT_MINIMUM_BLOCK_SIZE) -> (ptr: ^T, err: Allocator_Error) {
 	bootstrap: Growing_Arena
 	bootstrap.minimum_block_size = minimum_block_size
 	
@@ -84,7 +83,7 @@ growing_arena_bootstrap_new_by_offset :: proc($T: typeid, offset_to_arena: uintp
 	return
 }
 
-growing_arena_bootstrap_new_by_name :: proc($T: typeid, $field_name: string, minimum_block_size := DEFAULT_MINIMUM_BLOCK_SIZE) -> (ptr: ^T, err: mem.Allocator_Error) { 
+growing_arena_bootstrap_new_by_name :: proc($T: typeid, $field_name: string, minimum_block_size := DEFAULT_MINIMUM_BLOCK_SIZE) -> (ptr: ^T, err: Allocator_Error) { 
 	return growing_arena_bootstrap_new_by_offset(T, offset_of_by_string(T, field_name), minimum_block_size)
 }
 growing_arena_bootstrap_new :: proc{
@@ -99,7 +98,7 @@ growing_arena_allocator :: proc(arena: ^Growing_Arena) -> mem.Allocator {
 growing_arena_allocator_proc :: proc(allocator_data: rawptr, mode: mem.Allocator_Mode,
                              size, alignment: int,
                              old_memory: rawptr, old_size: int,
-                             location := #caller_location) -> (data: []byte, err: mem.Allocator_Error) {
+                             location := #caller_location) -> (data: []byte, err: Allocator_Error) {
 	arena := (^Growing_Arena)(allocator_data)
 	
 	switch mode {
@@ -160,4 +159,4 @@ growing_arena_temp_end :: proc(temp: Growing_Arena_Temp, loc := #caller_location
 
 growing_arena_check_temp :: proc(arena: ^Growing_Arena, loc := #caller_location) {
 	assert(arena.temp_count == 0, "Growing_Arena_Temp not been ended", loc)
-}
+}

core/mem/virtual/virtual.odin

@@ -3,6 +3,39 @@ package mem_virtual
 import "core:mem"
 import sync "core:sync/sync2"
 
+DEFAULT_PAGE_SIZE := uint(4096)
+
+Allocator_Error :: mem.Allocator_Error
+
+reserve :: proc(size: uint) -> (data: []byte, err: Allocator_Error) {
+	return _reserve(size)
+}
+
+commit :: proc(data: rawptr, size: uint) {
+	_commit(data, size)
+}
+
+reserve_and_commit :: proc(size: uint) -> (data: []byte, err: Allocator_Error) {
+	data = _reserve(size) or_return
+	commit(raw_data(data), size)
+	return
+}
+
+
+decommit :: proc(data: rawptr, size: uint) {
+	_decommit(data, size)
+}
+
+release :: proc(data: rawptr, size: uint) {
+	_release(data, size)
+}
+
+protect :: proc(data: rawptr, size: uint) -> bool {
+	return _protect(data, size)
+}
+
+
+
 Memory_Block :: struct {
 	prev: ^Memory_Block,
 	base: [^]byte,
@@ -11,18 +44,23 @@ Memory_Block :: struct {
 }
 
 
-memory_alloc :: proc(size: int) -> (block: ^Memory_Block, err: mem.Allocator_Error) {
+memory_alloc :: proc(size: int) -> (block: ^Memory_Block, err: Allocator_Error) {
+	align_formula :: proc "contextless" (size, align: uint) -> uint {
+		result := size + align-1
+		return result - result%align
+	}
+	
 	page_size := DEFAULT_PAGE_SIZE
 	
-	total_size     := size + size_of(Platform_Memory_Block)
+	total_size     := uint(size + size_of(Platform_Memory_Block))
 	base_offset    := uintptr(size_of(Platform_Memory_Block))
 	protect_offset := uintptr(0)
 	
 	do_protection := false
 	{ // overflow protection
-		rounded_size := mem.align_formula(size, page_size)
-		total_size     = rounded_size + 2*page_size
-		base_offset    = uintptr(page_size + rounded_size - size)
+		rounded_size := align_formula(uint(size), page_size)
+		total_size     = uint(rounded_size + 2*page_size)
+		base_offset    = uintptr(page_size + rounded_size - uint(size))
 		protect_offset = uintptr(page_size + rounded_size)
 		do_protection  = true
 	}
@@ -35,7 +73,7 @@ memory_alloc :: proc(size: int) -> (block: ^Memory_Block, err: mem.Allocator_Err
 	assert(pmblock.block.prev == nil)
 	
 	if (do_protection) {
-		platform_memory_protect(rawptr(uintptr(pmblock) + protect_offset), page_size)
+		protect(rawptr(uintptr(pmblock) + protect_offset), page_size)
 	}
 	
 	pmblock.block.size = size
@@ -67,10 +105,26 @@ memory_dealloc :: proc(block_to_free: ^Memory_Block) {
 
 Platform_Memory_Block :: struct {
 	block:      Memory_Block,
-	total_size: int,
+	total_size: uint,
 	prev, next: ^Platform_Memory_Block,
 } 
 
+platform_memory_alloc :: proc(total_size: uint) -> (block: ^Platform_Memory_Block, err: Allocator_Error) {
+	total_size := total_size
+	total_size = max(total_size, size_of(Platform_Memory_Block))
+	data := reserve_and_commit(total_size) or_return
+	block = (^Platform_Memory_Block)(raw_data(data))
+	block.total_size = total_size
+	return
+}
+
+
+platform_memory_free :: proc(block: ^Platform_Memory_Block) {
+	if block != nil {
+		release(block, block.total_size)
+	}
+}
+
 @(private)
 global_memory_block_mutex: sync.Mutex
 @(private)
@@ -78,7 +132,7 @@ global_platform_memory_block_sentinel: Platform_Memory_Block
 @(private)
 global_platform_memory_block_sentinel_set: bool
 
-@(init)
+@(private, init)
 platform_memory_init :: proc() {
 	if !global_platform_memory_block_sentinel_set {
 		_platform_memory_init()
@@ -87,16 +141,3 @@ platform_memory_init :: proc() {
 		global_platform_memory_block_sentinel_set = true
 	}
 }
-
-platform_memory_alloc :: proc(block_size: int) -> (^Platform_Memory_Block, mem.Allocator_Error) {
-	return _platform_memory_alloc(block_size)
-}
-
-
-platform_memory_free :: proc(block: ^Platform_Memory_Block) {
-	_platform_memory_free(block)
-}
-
-platform_memory_protect :: proc(memory: rawptr, size: int) {
-	_platform_memory_protect(memory, size)
-}

core/mem/virtual/virtual_windows.odin

@@ -2,8 +2,6 @@
 //+private
 package mem_virtual
 
-import "core:mem"
-
 foreign import Kernel32 "system:Kernel32.lib"
 
 LPSYSTEM_INFO :: ^SYSTEM_INFO
@@ -60,28 +58,38 @@ foreign Kernel32 {
 }
 
 
-_platform_memory_init :: proc() {
-	sys_info: SYSTEM_INFO
-	GetSystemInfo(&sys_info)
-	DEFAULT_PAGE_SIZE = max(DEFAULT_PAGE_SIZE, int(sys_info.dwPageSize))
-	assert(mem.is_power_of_two(uintptr(DEFAULT_PAGE_SIZE)))
-}
-
-_platform_memory_alloc :: proc(total_size: int) -> (pmblock: ^Platform_Memory_Block, err: mem.Allocator_Error) {
-	pmblock = (^Platform_Memory_Block)(VirtualAlloc(nil, uint(total_size), MEM_RESERVE|MEM_COMMIT, PAGE_READWRITE))
-	if pmblock == nil {
+_reserve :: proc(size: uint) -> (data: []byte, err: Allocator_Error) {
+	result := VirtualAlloc(nil, size, MEM_RELEASE, PAGE_READWRITE)
+	if result == nil {
 		err = .Out_Of_Memory
+		return
 	}
-	return 
+	data = ([^]byte)(result)[:size]
+	return
 }
 
-
-_platform_memory_free :: proc(block: ^Platform_Memory_Block) {
-	VirtualFree(block, 0, MEM_RELEASE)
+_commit :: proc(data: rawptr, size: uint) {
+	VirtualAlloc(data, size, MEM_COMMIT, PAGE_READWRITE)
 }
-
-_platform_memory_protect :: proc(memory: rawptr, size: int) -> bool {
+_decommit :: proc(data: rawptr, size: uint) {
+	VirtualFree(data, size, MEM_DECOMMIT)
+}
+_release :: proc(data: rawptr, size: uint) {
+	VirtualFree(data, 0, MEM_RELEASE)
+}
+_protect :: proc(data: rawptr, size: uint) -> bool {
 	old_protect: u32
-	ok := VirtualProtect(memory, uint(size), PAGE_NOACCESS, &old_protect)
+	ok := VirtualProtect(data, size, PAGE_NOACCESS, &old_protect)
 	return bool(ok)
-}
+}
+
+
+
+_platform_memory_init :: proc() {
+	sys_info: SYSTEM_INFO
+	GetSystemInfo(&sys_info)
+	DEFAULT_PAGE_SIZE = max(DEFAULT_PAGE_SIZE, uint(sys_info.dwPageSize))
+	
+	// is power of two
+	assert(DEFAULT_PAGE_SIZE != 0 && (DEFAULT_PAGE_SIZE & (DEFAULT_PAGE_SIZE-1)) == 0)
+}