Add Windows XP support merging PRs #6176 and #6177

Co-authored-by: Sugar-Baby <87747602+Sugar-Baby@users.noreply.github.com>
Co-authored-by: AtomAlpaca <66774326+AtomAlpaca@users.noreply.github.com>

Co-authored-by: nihui <171016+nihui@users.noreply.github.com>

.github/workflows/windows-xp-clang.yml

@@ -0,0 +1,62 @@
+name: windows-xp-clang
+on:
+  push:
+    branches: [master]
+    paths:
+    - '.github/workflows/windows-xp-clang.yml'
+    - 'toolchains/windows-xp-clang.toolchain.cmake'
+    - 'CMakeLists.txt'
+    - 'cmake/**'
+    - 'src/*'
+    - 'src/layer/*'
+    - 'src/layer/x86/**'
+    - 'tests/**'
+  pull_request:
+    branches: [master]
+    paths:
+    - '.github/workflows/windows-xp-clang.yml'
+    - 'toolchains/windows-xp-clang.toolchain.cmake'
+    - 'CMakeLists.txt'
+    - 'cmake/**'
+    - 'src/*'
+    - 'src/layer/*'
+    - 'src/layer/x86/**'
+    - 'tests/**'
+concurrency:
+  group: windows-xp-clang-${{ github.ref }}
+  cancel-in-progress: true
+permissions:
+  contents: read
+
+jobs:
+  windows:
+    name: Clang
+    runs-on: windows-2022
+
+    env:
+      UseMultiToolTask: true
+      NCNN_CMAKE_OPTIONS: -DNCNN_BUILD_TOOLS=OFF -DNCNN_BUILD_EXAMPLES=OFF -DNCNN_BUILD_TESTS=ON
+
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        submodules: true
+    - name: Set up Clang
+      run: choco install llvm --version=6.0.0 --allow-downgrade
+    - name: Verify Clang
+      run: |
+        clang --version
+        clang++ --version
+    - name: config
+      run: |
+        Invoke-WebRequest -Uri https://jaist.dl.sourceforge.net/project/mingw-w64/Toolchains%20targetting%20Win32/Personal%20Builds/mingw-builds/8.1.0/threads-posix/dwarf/i686-8.1.0-release-posix-dwarf-rt_v6-rev0.7z -OutFile i686-8.1.0-release-posix-dwarf-rt_v6-rev0.7z
+        7z x ./i686-8.1.0-release-posix-dwarf-rt_v6-rev0.7z
+        Add-Content -Path $env:GITHUB_ENV -Value "MINGW32_ROOT_PATH=${{ github.workspace }}\mingw32"
+        echo "${{ github.workspace }}\mingw32\bin;$env:PATH" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8
+    - name: build
+      run: |
+        mkdir build; cd build
+        cmake ${{ env.NCNN_CMAKE_OPTIONS }} -DCMAKE_TOOLCHAIN_FILE="../toolchains/windows-xp-clang.toolchain.cmake" -DNCNN_SIMPLEOCV=ON -DNCNN_SIMPLEOMP=ON -DNCNN_AVX2=OFF -DNCNN_AVX=OFF .. -G "MinGW Makefiles"
+        cmake --build . --config Release -j 4
+    - name: test
+      run: cd build; ctest -C Release --output-on-failure -j 4

.github/workflows/windows-xp-mingw.yml

@@ -0,0 +1,57 @@
+name: windows-xp-mingw
+on:
+  push:
+    branches: [master]
+    paths:
+    - '.github/workflows/windows-xp-mingw.yml'
+    - 'toolchains/windows-xp-mingw.toolchain.cmake'
+    - 'CMakeLists.txt'
+    - 'cmake/**'
+    - 'src/*'
+    - 'src/layer/*'
+    - 'src/layer/x86/**'
+    - 'tests/**'
+  pull_request:
+    branches: [master]
+    paths:
+    - '.github/workflows/windows-xp-mingw.yml'
+    - 'toolchains/windows-xp-mingw.toolchain.cmake'
+    - 'CMakeLists.txt'
+    - 'cmake/**'
+    - 'src/*'
+    - 'src/layer/*'
+    - 'src/layer/x86/**'
+    - 'tests/**'
+concurrency:
+  group: windows-xp-mingw-${{ github.ref }}
+  cancel-in-progress: true
+permissions:
+  contents: read
+
+jobs:
+  windows:
+    name: MinGW-w32
+    runs-on: windows-2022
+
+    env:
+      UseMultiToolTask: true
+      NCNN_CMAKE_OPTIONS: -DNCNN_BUILD_TOOLS=OFF -DNCNN_BUILD_EXAMPLES=OFF -DNCNN_BUILD_TESTS=ON
+
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        submodules: true
+
+    - name: config
+      run: |
+        Invoke-WebRequest -Uri https://jaist.dl.sourceforge.net/project/mingw-w64/Toolchains%20targetting%20Win32/Personal%20Builds/mingw-builds/8.1.0/threads-posix/dwarf/i686-8.1.0-release-posix-dwarf-rt_v6-rev0.7z -OutFile i686-8.1.0-release-posix-dwarf-rt_v6-rev0.7z
+        7z x ./i686-8.1.0-release-posix-dwarf-rt_v6-rev0.7z
+        Add-Content -Path $env:GITHUB_ENV -Value "MINGW32_ROOT_PATH=${{ github.workspace }}\mingw32"
+        Add-Content -Path $env:GITHUB_PATH -Value "${{ github.workspace }}\mingw32\bin"
+    - name: build
+      run: |
+        mkdir build; cd build
+        cmake ${{ env.NCNN_CMAKE_OPTIONS }} -DCMAKE_TOOLCHAIN_FILE="../toolchains/windows-xp-mingw.toolchain.cmake" -DNCNN_SIMPLEOCV=ON -DNCNN_AVX2=OFF -DNCNN_AVX=OFF -DNCNN_VULKAN=OFF .. -G "MinGW Makefiles"
+        cmake --build . --config Release -j 4
+    - name: test
+      run: cd build; ctest -C Release --output-on-failure -j 4

.github/workflows/windows-xp-msvc.yml

@@ -0,0 +1,56 @@
+name: windows-xp-msvc
+on:
+  push:
+    branches: [master]
+    paths:
+    - '.github/workflows/windows-xp-msvc.yml'
+    - 'toolchains/windows-xp-msvc.toolchain.cmake'
+    - 'CMakeLists.txt'
+    - 'cmake/**'
+    - 'src/*'
+    - 'src/layer/*'
+    - 'src/layer/x86/**'
+    - 'tests/**'
+  pull_request:
+    branches: [master]
+    paths:
+    - '.github/workflows/windows-xp-msvc.yml'
+    - 'toolchains/windows-xp-msvc.toolchain.cmake'
+    - 'CMakeLists.txt'
+    - 'cmake/**'
+    - 'src/*'
+    - 'src/layer/*'
+    - 'src/layer/x86/**'
+    - 'tests/**'
+concurrency:
+  group: windows-xp-msvc-${{ github.ref }}
+  cancel-in-progress: true
+permissions:
+  contents: read
+
+jobs:
+  windows:
+    name: MSVC
+    runs-on: windows-2022
+
+    env:
+      VS_INSTALL_DIR: C:\Program Files\Microsoft Visual Studio\2022\Enterprise
+      UseMultiToolTask: true
+      NCNN_CMAKE_OPTIONS: -DNCNN_BUILD_TOOLS=OFF -DNCNN_BUILD_EXAMPLES=OFF -DNCNN_BUILD_TESTS=ON
+
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        submodules: true
+    - name: config
+      shell: cmd
+      run: |
+        "C:\Program Files (x86)\Microsoft Visual Studio\Installer\setup.exe" modify --installPath "${{ env.VS_INSTALL_DIR }}" --channelId VisualStudio.17.Release --add Microsoft.VisualStudio.Component.WinXP  --add Microsoft.VisualStudio.Component.VC.Tools.X86.X64.Spectre --add Microsoft.VisualStudio.Component.VC.Tools.X86.X64 --add Microsoft.VisualStudio.Component.VC.Tools.X86.X64 --add Microsoft.VisualStudio.Component.VC.v141.xp --nocache --quiet
+        call "${{ env.VS_INSTALL_DIR }}\VC\Auxiliary\Build\vcvarsall.bat" x86
+    - name: build
+      run: |
+        mkdir build; cd build
+        cmake ${{ env.NCNN_CMAKE_OPTIONS }} -A WIN32 -G "Visual Studio 17 2022" -T v141_xp -DNCNN_SIMPLEOCV=ON -DNCNN_OPENMP=OFF -DNCNN_BUILD_WITH_STATIC_CRT=ON -DNCNN_AVX2=OFF -DNCNN_AVX=OFF -DCMAKE_TOOLCHAIN_FILE="../toolchains/windows-xp-msvc.toolchain.cmake" ..
+        cmake --build . --config Release -j 4
+    - name: test
+      run: cd build; ctest -C Release --output-on-failure -j 4

docs/developer-guide/build-ncnn-on-windows-xp.zh.md

@@ -0,0 +1,137 @@
+# Build ncnn on Windows XP
+
+> **Contributors:** [@Sugar-Baby](https://github.com/Sugar-Baby) and [@AtomAlpaca](https://github.com/AtomAlpaca)
+
+## 0. 环境准备
+
+#### 0.1 虚拟机设置
+
+我使用的是[我的MSDN](https://www.imsdn.cn/)提供的[Windows XP SP3 x64版本](https://www.imsdn.cn/operating-systems/windows-xp/)。虚拟机使用Oracle VM VirtualBox，内存4GB，存储空间64GB（C盘16GB，D盘48GB）。
+
+**在虚拟机关机的情况下**，点击虚拟机管理器界面的"设置"-"网络"-"高级"，将控制芯片改为PCnet-FAST III，混杂模式设置为拒绝，勾选接入网线，点击"OK"保存。重启虚拟机就可以连接上网络了。
+
+点击虚拟机界面的"设备"-"安装增强功能..."，在虚拟机中进入"我的电脑"，刷新后出现"VirtualBox Guest Additions (D: )"，右键选择"自动播放"，完成安装后重启。
+
+点击虚拟机界面的"设备"-"共享粘贴板"，设置为"双向"。点击"设备"-"共享文件夹"-"共享文件夹.."，点击右侧加号，在"共享文件夹路径"中选择"其他..."，然后选择需要共享的主机文件夹。勾选"自动挂载"和"固定分配"，点击"OK"保存。在虚拟机中进入"我的电脑"，刷新后出现'VBoxSvr' 上的 <主机文件夹名称>，双击进入就可以双向传输文件了。
+
+#### 0.2 开发环境配置
+
+浏览器推荐[Mypal 68](https://www.mypal-browser.org/download.html)，注意要选择32位版本。Windows XP自带ZIP文件解压。安装后就可以访问互联网了。
+
+从Github下载[w64devkit](https://github.com/skeeto/w64devkit)，选择x86版本。这里下载的是一个自解压的7z文件，在虚拟机中解压即可。
+
+在"开始"-"控制面板"-"切换到经典视图"-"系统"-"高级"-"环境变量"-"系统变量"中，选择Path，点击"编辑"，在字符串末尾加入一个分号(;)，然后粘贴w64devkit下bin文件夹的目录。点击"确定"保存之后可以打开命令提示符输入例如c++的命令验证是否成功加入环境变量。
+
+由于年代过于久远，Git的官方release已经没有兼容Windows XP的版本了。最后一个兼容的版本(1.9.5)可以在[这里](https://www.xiazaiba.com/html/29352.html)下载。
+
+为了使用Git，需要安装[Win32 OpenSSL](https://slproweb.com/products/Win32OpenSSL.html)。选择Win32 OpenSSL Light版本。这个过程中会附带安装VC++ 2022运行时库。
+
+如果因为协议、代理等问题不能在虚拟机中使用Git，也可以下载ZIP版本后在虚拟机中解压。
+
+需要手动下载[CMake最后支持Windows XP的版本](https://github.com/Kitware/CMake/releases/download/v3.10.3/cmake-3.10.3-win32-x86.zip)。建议解压在C:\Program Files下，并且需要设置系统变量，到CMake目录下的bin文件夹。具体可以参考上面w64devkit的方法。
+
+## 1. 编译
+
+### 1.1 使用 MinGW-w64
+
+运行
+
+```bash
+cd <ncnn-root-dir>
+mkdir build
+cd build
+cmake -DCMAKE_TOOLCHAIN_FILE=../toolchains/windows-xp-mingw.toolchain.cmake -DNCNN_VULKAN=OFF -DNCNN_SIMPLEOCV=ON -DNCNN_AVX=OFF -DCMAKE_BUILD_TYPE=Release -G "MinGW Makefiles" ..
+make -j2
+make install
+```
+
+由于平台性能的限制，Vulkan SDK 最低要求 Windows 7 SP1，XP 无法安装官方驱动和工具链，因此需要关闭Vulkan选项。同时需要使用简化版 OpenCV 替代库NCNN_SIMPLEOCV。
+
+### 1.2 使用 Clang
+
+需要先配置 MinGW-w64 环境，然后安装 Clang 6.0 或更高版本。
+
+```bash
+cd <ncnn-root-dir>
+mkdir build
+cd build
+cmake -DCMAKE_TOOLCHAIN_FILE=../toolchains/windows-xp-clang.toolchain.cmake -DNCNN_SIMPLEOCV=ON -DNCNN_SIMPLEOMP=ON -DNCNN_AVX=OFF -DCMAKE_BUILD_TYPE=Release -G "MinGW Makefiles" ..
+make -j2
+make install
+```
+
+### 1.3 使用 Visual Studio (MSVC)
+
+需要安装支持 Windows XP 的 v141_xp 工具集：
+
+1. 打开 Visual Studio 安装程序（工具 → 获取工具和功能）
+2. 选择"使用 C++ 的桌面开发"
+3. 在摘要部分选择"对 C++ 的 Windows XP 支持"
+4. 点击修改
+
+```bash
+cd <ncnn-root-dir>
+mkdir build
+cd build
+cmake -A WIN32 -G "Visual Studio 17 2022" -T v141_xp -DNCNN_SIMPLEOCV=ON -DNCNN_OPENMP=OFF -DNCNN_AVX=OFF -DNCNN_BUILD_WITH_STATIC_CRT=ON -DCMAKE_TOOLCHAIN_FILE=../toolchains/windows-xp-msvc.toolchain.cmake ..
+cmake --build . --config Release -j 2
+cmake --build . --config Release --target install
+```
+
+## 2. 测试
+
+### 2.1 benchncnn
+
+将benchmark目录下的所有文件复制到build/benchmark目录下。在命令提示符中cd到build/benchmark， 然后运行
+
+```bash
+benchncnn [测试的循环次数] [线程数] [节能模式]
+```
+
+其中，节能模式取值为0时关闭，为1时打开。
+
+### 2.2 examples
+
+从[这里](https://github.com/nihui/ncnn-assets/tree/master/models)可以下载到所有需要的param和bin文件。需要注意的是，ZF_faster_rcnn_final.bin开头的三个文件（.zip，.z01，.z02）最好先放在主机上解压出bin文件再传进虚拟机。
+
+把这些文件放在build/examples目录下。
+
+我写了一个bat脚本来批量测试这些模型：
+
+```batch
+@echo off
+setlocal enabledelayedexpansion
+
+set EXAMPLES_DIR=<ncnn-root-dir>\BUILD\EXAMPLES
+set IMAGE_PATH=<ncnn-root-dir>\IMAGES\256-ncnn.png
+set LOG_FILE=test_results.log
+
+echo NCNN Examples Test Results > %LOG_FILE%
+echo ========================= >> %LOG_FILE%
+echo Test started: %date% %time% >> %LOG_FILE%
+echo. >> %LOG_FILE%
+
+for %%f in ("%EXAMPLES_DIR%\*.exe") do (
+    set EXE_NAME=%%~nf
+    set EXE_PATH=%%f
+    echo Testing: !EXE_NAME! >> %LOG_FILE%
+    echo -------------------------------- >> %LOG_FILE%
+
+    !EXE_PATH! "%IMAGE_PATH%" >> %LOG_FILE% 2>&1
+
+    if errorlevel 1 (
+        echo [ERROR] !EXE_NAME! failed to run. >> %LOG_FILE%
+    ) else (
+        echo [SUCCESS] !EXE_NAME! completed. >> %LOG_FILE%
+    )
+    echo. >> %LOG_FILE%
+)
+
+echo Test finished: %date% %time% >> %LOG_FILE%
+echo Results saved to %LOG_FILE%
+endlocal
+```
+
+把这个bat脚本放在build/examples目录下，替换掉所有的`<ncnn-root-dir>`，双击运行。通过生成的test_results.log即可查看所有模型的结果。
+
+通过修改`set IMAGE_PATH=<ncnn-root-dir>\IMAGES\256-ncnn.png`中的路径来更换需要测试的文件。

docs/how-to-build/how-to-build.md

@@ -16,6 +16,10 @@ git submodule update --init
   - [Verification](#verification)
 - [Build for Windows x64 using Visual Studio Community 2017](#build-for-windows-x64-using-visual-studio-community-2017)
 - [Build for Windows x64 using MinGW-w64](#build-for-windows-x64-using-mingw-w64)
+- [Build for Windows XP (x86)](#build-for-windows-xp-x86)
+  - [Using MinGW-w64](#using-mingw-w64)
+  - [Using Clang](#using-clang)
+  - [Using Visual Studio (MSVC)](#using-visual-studio-msvc)
 - [Build for macOS](#build-for-macos)
 - [Build for ARM Cortex-A family with cross-compiling](#build-for-arm-cortex-a-family-with-cross-compiling)
 - [Build for Hisilicon platform with cross-compiling](#build-for-hisilicon-platform-with-cross-compiling)
@@ -263,6 +267,57 @@ cmake --build . --config Release --target install
 
 ***
 
+### Build for Windows XP (x86)
+
+> **Note:** Windows XP support is provided through collaborative contributions from [@Sugar-Baby](https://github.com/Sugar-Baby) and [@AtomAlpaca](https://github.com/AtomAlpaca).
+
+#### Using MinGW-w64
+
+Download mingw toolchain targeting 32 bit from [sourceforge](https://jaist.dl.sourceforge.net/project/mingw-w64/Toolchains%20targetting%20Win32/Personal%20Builds/mingw-builds/8.1.0/threads-posix/dwarf/i686-8.1.0-release-posix-dwarf-rt_v6-rev0.7z), extract and add environment variable named `MINGW32_ROOT_PATH` valued by `<your-path-to-mingw-root-path>`, and add `<your-path-to-mingw-root-path>/bin` to `PATH`.
+
+```shell
+mkdir build
+cd build
+cmake -DCMAKE_TOOLCHAIN_FILE="../toolchains/windows-xp-mingw.toolchain.cmake" -DNCNN_SIMPLEOCV=ON -DNCNN_AVX2=OFF -DNCNN_AVX=OFF -DNCNN_VULKAN=OFF .. -G "MinGW Makefiles"
+cmake --build . --config Release -j 4
+cmake --build . --config Release --target install
+```
+
+#### Using Clang
+
+Clang requires libraries from mingw. Configure mingw toolchain targeting 32-bit as described in the [MinGW-w64 section](#using-mingw-w64).
+
+Install Clang 6.0 or later.
+
+```shell
+mkdir build
+cd build
+cmake -DCMAKE_TOOLCHAIN_FILE="../toolchains/windows-xp-clang.toolchain.cmake" -DNCNN_SIMPLEOCV=ON -DNCNN_SIMPLEOMP=ON -DNCNN_AVX2=OFF -DNCNN_AVX=OFF .. -G "MinGW Makefiles"
+cmake --build . --config Release -j 4
+cmake --build . --config Release --target install
+```
+
+#### Using Visual Studio (MSVC)
+
+Install v141_xp toolset for Windows XP:
+
+1. Bring up the Visual Studio installer (Tools → Get Tools and Features)
+2. Select Desktop development with C++
+3. Select Windows XP support for C++ from the Summary section
+4. Click Modify
+
+```shell
+mkdir build
+cd build
+cmake -A WIN32 -G "Visual Studio 17 2022" -T v141_xp -DNCNN_SIMPLEOCV=ON -DNCNN_OPENMP=OFF -DNCNN_AVX2=OFF -DNCNN_AVX=OFF -DNCNN_BUILD_WITH_STATIC_CRT=ON -DCMAKE_TOOLCHAIN_FILE="../toolchains/windows-xp-msvc.toolchain.cmake" ..
+cmake --build . --config Release -j 2
+cmake --build . --config Release --target install
+```
+
+**Note:** The MSVC toolchain uses the `v141_xp` platform toolset for Windows XP compatibility. Vulkan is disabled for XP compatibility, and advanced CPU features (AVX, AVX2, AVX512) are disabled to ensure compatibility with older processors.
+
+***
+
 ### Build for macOS
 
 We've published ncnn to [brew](https://formulae.brew.sh/formula/ncnn#default) now, you can just use following method to install ncnn if you have the Xcode Command Line Tools installed.

src/cpu.cpp

@@ -153,7 +153,11 @@ __attribute__((constructor)) void ncnn_kmp_env_initializer()
     // and cpu core goes offline in powersave mode on android, which triggers abort
     // disable affinity capability, we handle thread affinity for openmp threads
 #if defined _WIN32
+#if _WIN32_WINNT >= 0x0600
     _putenv_s("KMP_AFFINITY", "disabled");
+#else
+    _putenv("KMP_AFFINITY=disabled");
+#endif
 #else
     setenv("KMP_AFFINITY", "disabled", 1);
 #endif
@@ -163,7 +167,11 @@ __attribute__((constructor)) void ncnn_kmp_env_initializer()
     // this happens when loading multiple libraries that are static linked openmp
     // just let it continue to work, it works well in most cases, at least it won't crash unexpectedly
 #if defined _WIN32
+#if _WIN32_WINNT >= 0x0600
     _putenv_s("KMP_DUPLICATE_LIB_OK", "1");
+#else
+    _putenv("KMP_DUPLICATE_LIB_OK=1");
+#endif
 #else
     setenv("KMP_DUPLICATE_LIB_OK", "1", 1);
 #endif

src/platform.h.in

@@ -67,6 +67,9 @@
 #if NCNN_THREADS
 #if defined _WIN32
 #define WIN32_LEAN_AND_MEAN
+#ifndef _WIN32_WINNT
+#define _WIN32_WINNT 0x0501
+#endif
 #include <windows.h>
 #include <process.h>
 #else
@@ -84,6 +87,7 @@ namespace ncnn {
 
 #if NCNN_THREADS
 #if defined _WIN32
+#if _WIN32_WINNT > _WIN32_WINNT_WINXP // Windows Vista and later
 class NCNN_EXPORT Mutex
 {
 public:
@@ -93,7 +97,6 @@ public:
     void unlock() { ReleaseSRWLockExclusive(&srwlock); }
 private:
     friend class ConditionVariable;
-    // NOTE SRWLock is available from windows vista
     SRWLOCK srwlock;
 };
 
@@ -109,6 +112,56 @@ private:
     CONDITION_VARIABLE condvar;
 };
 
+#else // Windows XP compatibility
+
+class NCNN_EXPORT Mutex
+{
+public:
+    Mutex() { InitializeCriticalSection(&cs); }
+    ~Mutex() { DeleteCriticalSection(&cs); }
+    void lock() { EnterCriticalSection(&cs); }
+    void unlock() { LeaveCriticalSection(&cs); }
+private:
+    friend class ConditionVariable;
+    CRITICAL_SECTION cs;
+};
+
+class NCNN_EXPORT ConditionVariable
+{
+public:
+    ConditionVariable() 
+    { 
+        signal_event = CreateEvent(0, FALSE, FALSE, 0); // Auto-reset event for signal()
+        broadcast_event = CreateEvent(0, TRUE, FALSE, 0); // Manual-reset event for broadcast()
+    }
+    ~ConditionVariable() 
+    { 
+        CloseHandle(signal_event); 
+        CloseHandle(broadcast_event); 
+    }
+    void wait(Mutex& mutex)
+    {
+        mutex.unlock();
+        HANDLE events[2] = { signal_event, broadcast_event };
+        WaitForMultipleObjects(2, events, FALSE, INFINITE); // Wait for either signal or broadcast
+        mutex.lock();
+    }
+    void broadcast() 
+    { 
+        SetEvent(broadcast_event); // Wake all threads
+        ResetEvent(broadcast_event); // Reset after waking all threads
+    }
+    void signal() 
+    { 
+        SetEvent(signal_event); // Wake one thread
+    }
+private:
+    HANDLE signal_event;
+    HANDLE broadcast_event;
+};
+
+#endif // _WIN32_WINNT > _WIN32_WINNT_WINXP
+
 static unsigned __stdcall start_wrapper(void* args);
 class NCNN_EXPORT Thread
 {

tests/test_cpu.cpp

@@ -107,8 +107,8 @@ static int test_cpu_powersave()
 #else
 
 #if defined _WIN32
-// Check SDK >= Win7
-#if _WIN32_WINNT >= _WIN32_WINNT_WIN7 // win7
+// Check SDK >= WinXP
+#if _WIN32_WINNT >= _WIN32_WINNT_WINXP // winxp
 
 static int test_cpu_info()
 {

toolchains/windows-xp-clang.toolchain.cmake

@@ -0,0 +1,33 @@
+# Windows XP Clang Toolchain
+# Supports building ncnn for Windows XP using Clang with MinGW libraries
+# Contributors: @Sugar-Baby and @AtomAlpaca
+
+set(CMAKE_SYSTEM_NAME Windows)
+
+if(DEFINED ENV{MINGW32_ROOT_PATH})
+    file(TO_CMAKE_PATH $ENV{MINGW32_ROOT_PATH} MINGW32_ROOT_PATH)
+else()
+    message(FATAL_ERROR "MINGW32_ROOT_PATH env must be defined")
+endif()
+
+set(CMAKE_C_COMPILER "clang.exe")
+set(CMAKE_CXX_COMPILER "clang++.exe")
+set(CMAKE_AR "$ENV{MINGW32_ROOT_PATH}/bin/ar.exe" CACHE FILEPATH "Archiver")
+set(CMAKE_RANLIB "$ENV{MINGW32_ROOT_PATH}/bin/ranlib.exe" CACHE FILEPATH "Ranlib")
+
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
+
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} --target=i686-pc-windows-gnu -D_WIN32_WINNT=0x0501 -static --sysroot=${MINGW32_ROOT_PATH} -D__STRICT_ANSI__")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} --target=i686-pc-windows-gnu -D_WIN32_WINNT=0x0501 -static --sysroot=${MINGW32_ROOT_PATH} -D__STRICT_ANSI__")
+
+# cache flags
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS}" CACHE STRING "c flags")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}" CACHE STRING "c++ flags")
+
+set(STATIC_LINK_FLAGS "-static")
+
+set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${STATIC_LINK_FLAGS}")
+set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} ${STATIC_LINK_FLAGS}")

toolchains/windows-xp-mingw.toolchain.cmake

@@ -0,0 +1,43 @@
+# Windows XP MinGW Toolchain
+# Supports building ncnn for Windows XP using MinGW-w64 32-bit toolchain
+# Contributors: @Sugar-Baby and @AtomAlpaca
+
+set(CMAKE_SYSTEM_NAME Windows)
+
+if(DEFINED ENV{MINGW32_ROOT_PATH})
+    file(TO_CMAKE_PATH $ENV{MINGW32_ROOT_PATH} MINGW32_ROOT_PATH)
+else()
+    message(FATAL_ERROR "MINGW32_ROOT_PATH env must be defined")
+endif()
+
+set(MINGW32_ROOT_PATH ${MINGW32_ROOT_PATH} CACHE STRING "root path to mingw toolchain")
+
+set(CMAKE_C_COMPILER "${MINGW32_ROOT_PATH}/bin/i686-w64-mingw32-gcc.exe")
+set(CMAKE_CXX_COMPILER "${MINGW32_ROOT_PATH}/bin/i686-w64-mingw32-g++.exe")
+
+set(CMAKE_FIND_ROOT_PATH "${MINGW32_ROOT_PATH}/i686-w64-mingw32")
+
+if(NOT CMAKE_FIND_ROOT_PATH_MODE_PROGRAM)
+    set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+endif()
+if(NOT CMAKE_FIND_ROOT_PATH_MODE_LIBRARY)
+    set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+endif()
+if(NOT CMAKE_FIND_ROOT_PATH_MODE_INCLUDE)
+    set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+endif()
+if(NOT CMAKE_FIND_ROOT_PATH_MODE_PACKAGE)
+    set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
+endif()
+
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -D_WIN32_WINNT=0x0501 -march=i686 -static -UMINGW_HAS_SECURE_API")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -D_WIN32_WINNT=0x0501 -march=i686 -static -UMINGW_HAS_SECURE_API")
+
+# cache flags
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS}" CACHE STRING "c flags")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}" CACHE STRING "c++ flags")
+
+set(STATIC_LINK_FLAGS "-static -fopenmp")
+
+set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${STATIC_LINK_FLAGS}")
+set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} ${STATIC_LINK_FLAGS}")

toolchains/windows-xp-msvc.toolchain.cmake

@@ -0,0 +1,31 @@
+# Windows XP MSVC Toolchain
+# Supports Visual Studio 2017 (v141) and later with XP compatibility
+# Contributors: @Sugar-Baby and @AtomAlpaca
+
+set(CMAKE_SYSTEM_NAME Windows)
+set(CMAKE_SYSTEM_VERSION 5.1)
+set(CMAKE_C_COMPILER cl)
+set(CMAKE_CXX_COMPILER cl)
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /D_WIN32_WINNT=0x0501 /DWINVER=0x0501 /EHsc")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /D_WIN32_WINNT=0x0501 /DWINVER=0x0501 /EHsc")
+set(CMAKE_GENERATOR_TOOLSET "v141_xp" CACHE STRING "Platform Toolset" FORCE)
+
+# Disabling AVX will automatically disable newer instruction sets (AVX2, AVX512, etc.)
+set(NCNN_VULKAN OFF CACHE BOOL "Disable Vulkan for Windows XP" FORCE)
+set(CMAKE_GENERATOR_PLATFORM "Win32" CACHE STRING "Platform" FORCE)
+set(NCNN_SIMPLEOCV ON CACHE BOOL "Use simple OpenCV implementation" FORCE)
+
+# cache flags
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS}" CACHE STRING "c flags")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}" CACHE STRING "c++ flags")
+
+set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
+set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
+set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
+
+message(STATUS "Windows XP MSVC Toolchain configured")
+message(STATUS "  Platform Toolset: ${CMAKE_GENERATOR_TOOLSET}")
+message(STATUS "  Platform: ${CMAKE_GENERATOR_PLATFORM}")
+message(STATUS "  Runtime Library: ${CMAKE_MSVC_RUNTIME_LIBRARY}")
+message(STATUS "  Vulkan: ${NCNN_VULKAN}")
+message(STATUS "  Build Type: ${CMAKE_BUILD_TYPE}")