cpp: Add GGUFReader.cpp and GGUFReader.kt to read GGUF files #34

Author: shubham0204

smollm/src/main/cpp/GGUFReader.cpp

@@ -0,0 +1,31 @@
+#include "gguf.h"
+#include <jni.h>
+#include <string>
+
+extern "C"
+JNIEXPORT jlong JNICALL
+Java_io_shubham0204_smollm_GGUFReader_getGGUFContextNativeHandle(JNIEnv *env, jobject thiz, jstring modelPath) {
+    jboolean isCopy = true;
+    const char *modelPathCStr = env->GetStringUTFChars(modelPath, &isCopy);
+    gguf_init_params initParams = {
+            .no_alloc = true,
+            .ctx = nullptr
+    };
+    gguf_context *ggufContext = gguf_init_from_file(modelPathCStr, initParams);
+    env->ReleaseStringUTFChars(modelPath, modelPathCStr);
+    return reinterpret_cast<jlong>(ggufContext);
+}
+
+extern "C"
+JNIEXPORT jlong JNICALL
+Java_io_shubham0204_smollm_GGUFReader_getContextSize(JNIEnv *env, jobject thiz, jlong nativeHandle) {
+    gguf_context *ggufContext = reinterpret_cast<gguf_context *>(nativeHandle);
+    int64_t architectureKeyId = gguf_find_key(ggufContext, "general.architecture");
+    if (architectureKeyId == -1) return -1;
+    std::string architecture = gguf_get_val_str(ggufContext, architectureKeyId);
+    std::string contextLengthKey = architecture + ".context_length";
+    int64_t contextLengthKeyId = gguf_find_key(ggufContext, contextLengthKey.c_str());
+    if (contextLengthKeyId == -1) return -1;
+    uint32_t contextLength = gguf_get_val_u32(ggufContext, contextLengthKeyId);
+    return contextLength;
+}

smollm/src/main/java/io/shubham0204/smollm/GGUFReader.kt

@@ -0,0 +1,55 @@
+/*
+ * Copyright (C) 2025 Shubham Panchal
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.shubham0204.smollm
+
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+
+class GGUFReader {
+    companion object {
+        init {
+            System.loadLibrary("ggufreader")
+        }
+    }
+
+    private var nativeHandle: Long = 0L
+
+    suspend fun load(modelPath: String) =
+        withContext(Dispatchers.IO) {
+            nativeHandle = getGGUFContextNativeHandle(modelPath)
+        }
+
+    fun getContextSize(): Long? {
+        assert(nativeHandle != 0L) { "Use GGUFReader.load() to initialize the reader" }
+        val contextSize = getContextSize(nativeHandle)
+        return if (contextSize == -1L) {
+            null
+        } else {
+            contextSize
+        }
+    }
+
+    /**
+     * Returns the native handle (pointer to gguf_context created on the native side)
+     */
+    private external fun getGGUFContextNativeHandle(modelPath: String): Long
+
+    /**
+     * Read the context size (in no. of tokens) from the GGUF file, given the native handle
+     */
+    private external fun getContextSize(nativeHandle: Long): Long
+}