emulator: opengl: Back-port GLES emulation from the master tree.

The modules here are only built when BUILD_EMULATOR_OPENGL is defined to true
in your environment or your BoardConfig.mk (see tools/emulator/opengl/Android.mk)

Change-Id: I5f32c35b4452fb5a7b4d5f9fc5870ec1da6032e6

tools/emulator/opengl/host/libs/libOpenglRender/ReadBuffer.cpp

@@ -0,0 +1,73 @@
+/*
+* Copyright (C) 2011 The Android Open Source Project
+*
+* 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.
+*/
+#include "ReadBuffer.h"
+#include <string.h>
+#include <assert.h>
+#include <limits.h>
+#include "ErrorLog.h"
+
+ReadBuffer::ReadBuffer(IOStream *stream, size_t bufsize)
+{
+    m_size = bufsize;
+    m_stream = stream;
+    m_buf = (unsigned char*)malloc(m_size*sizeof(unsigned char));
+    m_validData = 0;
+    m_readPtr = m_buf;
+}
+
+ReadBuffer::~ReadBuffer()
+{
+    free(m_buf);
+}
+
+int ReadBuffer::getData()
+{
+    if ((m_validData > 0) && (m_readPtr > m_buf)) {
+        memmove(m_buf, m_readPtr, m_validData);
+    }
+    // get fresh data into the buffer;
+    size_t len = m_size - m_validData;
+    if (len==0) {
+        //we need to inc our buffer
+        size_t new_size = m_size*2;
+        unsigned char* new_buf;
+        if (new_size < m_size) { // overflow check
+            new_size = INT_MAX;
+        }
+
+        new_buf = (unsigned char*)realloc(m_buf, new_size);
+        if (!new_buf) {
+            ERR("Failed to alloc %d bytes for ReadBuffer\n", new_size);
+            return -1;
+        }
+        m_size = new_size;
+        m_buf  = new_buf;
+        len    = m_size - m_validData;
+    }
+    m_readPtr = m_buf;
+    if (NULL != m_stream->read(m_buf + m_validData, &len)) {
+        m_validData += len;
+        return len;
+    }
+    return -1;
+}
+
+void ReadBuffer::consume(size_t amount)
+{
+    assert(amount <= m_validData);
+    m_validData -= amount;
+    m_readPtr += amount;
+}