156 lines
4.0 KiB
C
156 lines
4.0 KiB
C
/*
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SST_SysMem_Win32.c
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Author: Patrick Baggett <ptbaggett@762studios.com>
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Created: 12/23/2011
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Purpose:
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libsst-os system memory allocation functions for Win32 platforms (Windows 7 or later)
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License:
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This program is free software. It comes without any warranty, to
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the extent permitted by applicable law. You can redistribute it
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and/or modify it under the terms of the Do What The Fuck You Want
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To Public License, Version 2, as published by Sam Hocevar. See
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http://sam.zoy.org/wtfpl/COPYING for more details.
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*/
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#include "Win32Private.h"
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#include <SST/SST_SysMem.h>
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#include <SST/SST_Assert.h>
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static uint32_t cached_pagesize;
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void __libsst_init_pagesize()
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{
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SYSTEM_INFO info;
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GetNativeSystemInfo(&info);
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cached_pagesize = (uint32_t)info.dwPageSize;
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}
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/* Round an allocation of 'amount' bytes to be a multiple of 'pageSize' */
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static size_t roundToPage(uint32_t pageSize, size_t amount)
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{
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size_t rounded;
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/* ASSUMPTION: pageSize is a power of two */
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/*
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Algorithm: Round up allocation to the nearest page.
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[1] x & (pageSize-1) = Bytes that are extra parts of a page
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[2] x & (~(pageSize-1)) = Bytes that are whole pages.
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Start with [2] bytes. If [1] is non-zero, then add page size.
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*/
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rounded = amount & (~(pageSize-1));
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if(amount & (pageSize-1))
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rounded += pageSize;
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return rounded;
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}
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/*************************************************************************/
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uint64_t SST_OS_GetMemorySize()
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{
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ULONGLONG mem = 0;
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if(GetPhysicallyInstalledSystemMemory(&mem))
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return (uint64_t)mem;
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return 0;
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}
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/*************************************************************************/
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uint32_t SST_OS_GetPageSize()
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{
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return cached_pagesize;
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}
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/*************************************************************************/
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void* SST_OS_AllocPages(size_t allocBytes)
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{
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SST_OS_DebugAssert(allocBytes > 0, "Allocating 0 bytes is not allowed");
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return VirtualAllocEx(GetCurrentProcess(), NULL, roundToPage(SST_OS_GetPageSize(), allocBytes), MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE);
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}
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/*************************************************************************/
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int SST_OS_FreePages(void* pageBase, size_t nrBytes)
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{
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uintptr_t addr;
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uint32_t pageSize;
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SST_OS_DebugAssert(pageBase != NULL, "Base address may not be NULL");
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SST_OS_DebugAssert(nrBytes > 0, "The number of bytes to free may not be zero");
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addr = (uintptr_t)pageBase;
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pageSize = SST_OS_GetPageSize();
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/* Check if address is aligned to page boundary */
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if(addr & (pageSize-1))
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return -1;
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/* Free the pages */
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if(VirtualFreeEx(GetCurrentProcess(), pageBase, roundToPage(pageSize, nrBytes), MEM_DECOMMIT | MEM_RELEASE) != 0)
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return 1;
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return 0;
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}
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/*************************************************************************/
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int SST_OS_ProtectPages(void* pageBase, size_t nrBytes, int protectFlags)
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{
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uintptr_t addr;
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uint32_t pageSize;
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DWORD newFlags = PAGE_NOACCESS;
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SST_OS_DebugAssert(pageBase != NULL, "Base address may not be NULL");
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SST_OS_DebugAssert(nrBytes > 0, "The number of bytes to free may not be zero");
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addr = (uintptr_t)pageBase;
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pageSize = SST_OS_GetPageSize();
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/* Check if address is aligned to page boundary */
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if(addr & (pageSize-1))
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return -1;
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/* Microsoft doesn't believe in bitfields. This switch brought to you by a poor design decision */
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switch(protectFlags)
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{
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/* r/o */
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case SST_PROTECT_READ: newFlags = PAGE_READONLY; break;
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/* r/w, w/o */
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case SST_PROTECT_READ | SST_PROTECT_WRITE:
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case SST_PROTECT_WRITE: newFlags = PAGE_READWRITE; break; /* Win32 doesn't have w/o */
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/* x/o */
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case SST_PROTECT_EXEC: newFlags = PAGE_EXECUTE; break;
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/* w/x */
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case SST_PROTECT_WRITE | SST_PROTECT_EXEC: newFlags = PAGE_EXECUTE_READWRITE; break;
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/* r/x */
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case SST_PROTECT_READ | SST_PROTECT_EXEC: newFlags = PAGE_EXECUTE_READ; break;
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/* r/w/x */
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case SST_PROTECT_READ | SST_PROTECT_WRITE | SST_PROTECT_EXEC: newFlags = PAGE_EXECUTE_READWRITE; break;
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}
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if(VirtualProtectEx(GetCurrentProcess(), (void*)addr, roundToPage(pageSize, nrBytes), newFlags, NULL) != 0)
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return 1;
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return 0;
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}
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