Cross-platform wrappers for OS-level virtual memory management. More...

#include "base/base_macros.h"
#include "base/base_types.h"

Include dependency graph for mem_os.h:

This graph shows which files directly or indirectly include this file:

Functions
usize	mem_os_page_size (void)
	Retrieves the operating system's virtual memory page size.
void *	mem_os_reserve (usize size)
	Reserves a contiguous block of virtual address space.
b32	mem_os_commit (void *ptr, usize size)
	Commits physical RAM to a previously reserved virtual address block.
void	mem_os_decommit (void *ptr, usize size)
	Decommits physical RAM, returning it to the OS.
void	mem_os_release (void *ptr, usize size)
	Releases a reserved virtual address block entirely back to the OS.

Detailed Description

Cross-platform wrappers for OS-level virtual memory management.

Provides a unified API over Windows VirtualAlloc and POSIX mmap. Separates the concepts of reserving virtual address space from committing physical RAM pages. This is the lowest layer of the memory subsystem — most application code should use MemArena rather than calling these directly.

Reserve vs Commit

Virtual memory operates in two phases:

Reserve: Claims a range of virtual address space. Uses no physical RAM. Near-instant regardless of size. Think of it as calling dibs on addresses.
Commit: Maps physical RAM to a sub-range of a reserved block. Only committed pages can be read or written.

Usage: // Reserve 1 GB (free on all modern OSes, no physical RAM used):

void *mem = mem_os_reserve(GB(1));

// Commit only the first 64 KB (physical RAM now used):

mem_os_commit(mem, KB(64));

// Use the committed memory:

int *buf = (int *)mem;

buf[0] = 42;

// Return physical RAM but keep the address space:

mem_os_decommit(mem, KB(64));

// Release the entire reservation:

mem_os_release(mem, GB(1));

KB
#define KB(x)
Definition base_types.h:119

GB
#define GB(x)
Definition base_types.h:121

mem_os_release
void mem_os_release(void *ptr, usize size)
Releases a reserved virtual address block entirely back to the OS.
Definition mem_os.c:50

mem_os_commit
b32 mem_os_commit(void *ptr, usize size)
Commits physical RAM to a previously reserved virtual address block.
Definition mem_os.c:29

mem_os_reserve
void * mem_os_reserve(usize size)
Reserves a contiguous block of virtual address space.
Definition mem_os.c:18

mem_os_decommit
void mem_os_decommit(void *ptr, usize size)
Decommits physical RAM, returning it to the OS.
Definition mem_os.c:39

Definition in file mem_os.h.

Functions

Detailed Description