From c723ec4054112b1ae7e9452c587fc743b3560b7a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=91=D1=80=D0=B0=D0=BD=D0=B8=D0=BC=D0=B8=D1=80=20=D0=9A?=
 =?UTF-8?q?=D0=B0=D1=80=D0=B0=D1=9F=D0=B8=D1=9B?=
 <branimirkaradzic@gmail.com>
Date: Tue, 31 Dec 2024 08:24:43 -0800
Subject: [PATCH] Added memory map/unmap functions.

---
 include/bx/os.h | 12 +++++++
 src/os.cpp      | 87 +++++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 96 insertions(+), 3 deletions(-)

diff --git a/include/bx/os.h b/include/bx/os.h
index 4c0301909..3515d0cba 100644
--- a/include/bx/os.h
+++ b/include/bx/os.h
@@ -16,6 +16,9 @@
 #	define BX_DL_EXT "so"
 #endif //
 
+BX_ERROR_RESULT(kErrorMemoryMapFailed,   BX_MAKEFOURCC('b', 'x', '8', '0') );
+BX_ERROR_RESULT(kErrorMemoryUnmapFailed, BX_MAKEFOURCC('b', 'x', '8', '1') );
+
 namespace bx
 {
 	///
@@ -58,6 +61,15 @@ namespace bx
 	///
 	[[noreturn]] void exit(int32_t _exitCode);
 
+	///
+	void* memoryMap(void* _address, size_t _size, Error* _err);
+
+	///
+	void memoryUnmap(void* _address, size_t _size, Error* _err);
+
+	///
+	size_t memoryPageSize();
+
 } // namespace bx
 
 #include "inline/os.inl"
diff --git a/src/os.cpp b/src/os.cpp
index e24b9aa5e..039be6f6d 100644
--- a/src/os.cpp
+++ b/src/os.cpp
@@ -10,7 +10,7 @@
 #if BX_CRT_MSVC
 #	include <direct.h>
 #else
-#	include <unistd.h>
+#	include <unistd.h> // syscall, _SC_PAGESIZE
 #endif // BX_CRT_MSVC
 
 #if BX_PLATFORM_WINDOWS || BX_PLATFORM_WINRT
@@ -43,13 +43,14 @@
 
 #	if BX_PLATFORM_ANDROID
 #		include <malloc.h> // mallinfo
-#	elif   BX_PLATFORM_LINUX     \
+#	elif   BX_PLATFORM_LINUX \
 		|| BX_PLATFORM_RPI
 #		include <stdio.h>  // fopen
-#		include <unistd.h> // syscall
+#		include <sys/mman.h>
 #		include <sys/syscall.h>
 #	elif BX_PLATFORM_OSX
 #		include <mach/mach.h> // mach_task_basic_info
+#		include <sys/mman.h>
 #	endif // BX_PLATFORM_ANDROID
 #endif // BX_PLATFORM_
 
@@ -373,4 +374,84 @@ namespace bx
 		::exit(_exitCode);
 	}
 
+	void* memoryMap(void* _address, size_t _size, Error* _err)
+	{
+		BX_ERROR_SCOPE(_err);
+
+#if BX_PLATFORM_LINUX || BX_PLATFORM_OSX
+		constexpr int32_t flags = 0
+			| MAP_ANON
+			| MAP_PRIVATE
+			;
+
+		void* result = mmap(_address, _size, PROT_READ | PROT_WRITE, flags, -1 /*fd*/, 0 /*offset*/);
+
+		if (MAP_FAILED == result)
+		{
+			BX_ERROR_SET(
+				  _err
+				, kErrorMemoryMapFailed
+				, "kErrorMemoryMapFailed"
+				);
+
+			return NULL;
+		}
+
+		return result;
+#elif BX_PLATFORM_WINDOWS
+		void* result = VirtualAlloc(_address, _size, MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE);
+
+		return result;
+#else
+		BX_UNUSED(_address, _size);
+		BX_ERROR_SET(_err, kErrorMemoryMapFailed, "Not implemented!");
+		return NULL;
+#endif // BX_PLATFORM_*
+	}
+
+	void memoryUnmap(void* _address, size_t _size, Error* _err)
+	{
+		BX_ERROR_SCOPE(_err);
+
+#if BX_PLATFORM_LINUX || BX_PLATFORM_OSX
+		int32_t result = munmap(_address, _size);
+
+		if (-1 == result)
+		{
+			BX_ERROR_SET(
+				  _err
+				, kErrorMemoryUnmapFailed
+				, "kErrorMemoryUnmapFailed"
+				);
+		}
+#elif BX_PLATFORM_WINDOWS
+		if (!VirtualFree(_address, _size, MEM_RELEASE) )
+		{
+			BX_ERROR_SET(
+				  _err
+				, kErrorMemoryUnmapFailed
+				, "kErrorMemoryUnmapFailed"
+				);
+		}
+#else
+		BX_UNUSED(_address, _size);
+		BX_ERROR_SET(_err, kErrorMemoryUnmapFailed, "Not implemented!");
+#endif // BX_PLATFORM_*
+	}
+
+	size_t memoryPageSize()
+	{
+		size_t pageSize;
+#if BX_PLATFORM_WINDOWS
+		SYSTEM_INFO si; //SystemInfo si;
+		memSet(&si, 0, sizeof(si) );
+		::GetSystemInfo(&si);
+		pageSize = si.dwAllocationGranularity;
+#else
+		pageSize = sysconf(_SC_PAGESIZE);
+#endif // BX_PLATFORM_WINDOWS
+
+		return pageSize;
+	}
+
 } // namespace bx