mem_os.c

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#include "memory/mem_os.h"
#include "base/base_macros.h"
 
#if OS_WINDOWS
#   include <windows.h>
#elif OS_LINUX || OS_MAC
#   include <sys/mman.h>
#endif
 
void *
os_mem_reserve(usize size)
{
#if OS_WINDOWS
    return VirtualAlloc(0, size, MEM_RESERVE, PAGE_NOACCESS);
#elif OS_LINUX || OS_MAC
    void *ptr = mmap(0, size, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
    return (ptr == MAP_FAILED) ? 0 : ptr;
#endif
}
 
b32
os_mem_commit(void *ptr, usize size)
{
#if OS_WINDOWS
    return VirtualAlloc(ptr, size, MEM_COMMIT, PAGE_READWRITE) != 0;
#elif OS_LINUX || OS_MAC
    return mprotect(ptr, size, PROT_READ | PROT_WRITE) == 0;
#endif
}
 
void
os_mem_decommit(void *ptr, usize size)
{
#if OS_WINDOWS
    VirtualFree(ptr, size, MEM_DECOMMIT);
#elif OS_LINUX || OS_MAC
    mprotect(ptr, size, PROT_NONE);
    madvise(ptr, size, MADV_DONTNEED);
#endif
}
 
void
os_mem_release(void *ptr, usize size)
{
#if OS_WINDOWS
    // Note: Windows requires size to be 0 when using MEM_RELEASE
    (void)size;
    VirtualFree(ptr, 0, MEM_RELEASE);
#elif OS_LINUX || OS_MAC
    munmap(ptr, size);
#endif
}