Restructure os code

programs/os_windows.kl

@@ -0,0 +1,63 @@
+#import "kernel32.kl"
+#import "base.kl"
+
+PAGE_SIZE :: 4096
+Memory :: struct
+  commit : SizeU
+  reserve: SizeU
+  data   : *U8
+
+process_heap: HANDLE
+allocate :: (size: U64): *void
+  if process_heap == 0
+    process_heap = GetProcessHeap()
+  return HeapAlloc(process_heap, 0, size)
+
+reserve :: (size: SizeU): Memory
+  result := Memory{reserve=align_up(size, PAGE_SIZE)}
+  result.data = VirtualAlloc(
+    flProtect        = PAGE_READWRITE,
+    dwSize           = result.reserve,
+    flAllocationType = MEM_RESERVE,
+    lpAddress        = 0)->*U8
+  return result
+
+commit :: (m: *Memory, size: SizeU): Bool
+  commit_size := align_up(size, PAGE_SIZE)
+  total_commit := m.commit + commit_size
+  clamped_commit := clamp_top_sizeu(total_commit, m.reserve)
+  adjusted_commit := clamped_commit - m.commit
+  if adjusted_commit != 0
+    result := VirtualAlloc(
+      lpAddress        = (m.data + m.commit)->*void,
+      dwSize           = adjusted_commit,
+      flAllocationType = MEM_COMMIT,
+      flProtect        = PAGE_READWRITE,
+    )
+    m.commit += adjusted_commit
+    return true
+  return false
+
+release :: (m: *Memory)
+  result := VirtualFree(m.data->*void, 0, MEM_RELEASE)
+  if result != 0
+    m.data    = 0
+    m.commit  = 0
+    m.reserve = 0
+
+print :: (string: String16)
+  handle := GetStdHandle(STD_OUTPUT_HANDLE)
+  WriteConsoleW(handle, (string.str)->*void, string.len->DWORD, 0, 0)
+
+performance_frequency: F64
+time :: (): F64
+  query: LARGE_INTEGER
+  if !performance_frequency
+    err := QueryPerformanceFrequency(&query)
+    assert(err != 0)
+    performance_frequency = query->F64
+
+  err := QueryPerformanceCounter(&query)
+  assert(err != 0)
+  result := query->F64 / performance_frequency
+  return result