[Feat] (Pipe): land the P4a contract - the resource target enum, the framebuffer target byte, the texture params' builtin sampler, the sampler-parameter field table, four subsystem bits, seven dirty arms and the program archive codec

MobileGL/MG_Test/Pipe/SamplerEmitTest.cpp

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+// MobileGL - MobileGL/MG_Test/Pipe/SamplerEmitTest.cpp
+// Copyright (c) 2025-2026 MobileGL-Dev
+// Licensed under the GNU Lesser General Public License v3.0:
+//   https://www.gnu.org/licenses/gpl-3.0.txt
+//   https://www.gnu.org/licenses/lgpl-3.0.txt
+// SPDX-License-Identifier: LGPL-3.0-only
+// End of Source File Header
+
+// P4a's sampler family: the content-addressed sampler CSO, the identity-addressed sampler view
+// per texture object, and the set_sampler_views / bind_sampler_states unit sets.
+//
+// THIS SUITE IS A NAMED GATE (`ctest -R 'SamplerEmit\.'`), and its negative control is a
+// script that stops the conversion copying SamplerParameters::borderColorForm and expects this
+// suite to go red NAMING that field - which it must, because all three border-colour
+// representations are always numerically populated and the value alone cannot say which driver
+// entry point to use.
+//
+// THE ONE CASE THAT LOOKS LIKE PARANOIA AND IS NOT: SamplerParameters is 100 bytes with THREE
+// BYTES OF TRAILING PADDING, so a cache that hashes or memcmps the object's own bytes reads
+// uninitialised memory and mints a fresh CSO per call - a 256-entry cache with a hit rate of
+// zero, and nobody notices, because the pixels are right. The case that writes garbage into
+// the padding through a byte pointer is what turns that into a red gate.
+//
+// THE SUITE IS `SamplerEmit`, not `SamplerEmitTest`: the file is XTest.cpp and the suite is X,
+// this directory's convention, and it is what the gates grep for.
+//
+// THE TARGET AND ITS ctest REGISTRATION ARE THE CONTRACT COMMIT'S; THE CONTENTS ARE NOT: the
+// applier-side cases are the wire commits' and the emitter-side cases are the client
+// package's, and neither has to come back to MG_Test/Pipe/CMakeLists.txt to add one.
+//
+// IT HAS ITS OWN main() for ResourceEmitTest's reason. Every case is a visible SKIP in a pull
+// build rather than a vanishing test, so `ctest -N` stays name-for-name identical between the
+// pull and the push trees.
+
+#include <gtest/gtest.h>
+
+#include <filesystem>
+#include <string>
+#include <system_error>
+
+#if defined(_WIN32)
+#include <process.h>
+#else
+#include <unistd.h>
+#endif
+
+#include "Includes.h"
+#include <MG_Pipe/MGPipe.h>
+#if MOBILEGL_PIPE_PUSH
+#include <MG_Impl/Pipe/SamplerEmit.h>
+#include <MG_Pipe/PipeApply.h>
+#endif
+
+using namespace MobileGL;
+using namespace MobileGL::MG_Pipe;
+
+namespace {
+    String g_logPath;
+
+    int ProcessId() {
+#if defined(_WIN32)
+        return _getpid();
+#else
+        return static_cast<int>(getpid());
+#endif
+    }
+} // namespace
+
+// See FramebufferEmitTest's twin for why this is a shape pin rather than a placeholder.
+TEST(SamplerEmit, TheEmitterIsOneNeverDestroyedProcessSingleton) {
+#if MOBILEGL_PIPE_PUSH
+    EXPECT_EQ(&MGPipeSamplerEmitterInstance(), &MGPipeSamplerEmitterInstance());
+    // One bit for the whole sampler family - the CSO, the view and all three unit sets,
+    // including set_shader_images, whose emitter lives in ImageEmit.h. An operator switching
+    // samplers off has to get the whole family's legacy arm, not two thirds of it.
+    EXPECT_TRUE(kMGPipeWiredSamplerSubsystem == 0 ||
+                kMGPipeWiredSamplerSubsystem == kMGPipeSubsystemSamplers);
+#else
+    GTEST_SKIP() << "MOBILEGL_PIPE_PUSH is off: there is no client emitter in a pull build";
+#endif
+}
+
+int main(int argc, char** argv) {
+    namespace fs = std::filesystem;
+    const fs::path path =
+        fs::temp_directory_path() / ("mobilegl-sampleremit-test-" + std::to_string(ProcessId()) + ".log");
+    std::error_code ec;
+    fs::remove(path, ec);
+    g_logPath = path.string();
+#if defined(_WIN32)
+    _putenv_s("MOBILEGL_LOG_FILE_PATH", g_logPath.c_str());
+#else
+    setenv("MOBILEGL_LOG_FILE_PATH", g_logPath.c_str(), 1);
+#endif
+    ::testing::InitGoogleTest(&argc, argv);
+    const int rc = RUN_ALL_TESTS();
+    fs::remove(path, ec);
+    return rc;
+}