[Mesa-dev] [wip 1/9] glsl: memory_writer helper class for data serialization

[Tapani Pälli]

Class will be used by the shader binary cache implementation.

Signed-off-by: Tapani Pälli <tapani.palli at intel.com>
---
 src/glsl/memory_writer.h | 147 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 147 insertions(+)
 create mode 100644 src/glsl/memory_writer.h

diff --git a/src/glsl/memory_writer.h b/src/glsl/memory_writer.h
new file mode 100644
index 0000000..a6c6b55
--- /dev/null
+++ b/src/glsl/memory_writer.h
@@ -0,0 +1,147 @@
+/* -*- c++ -*- */
+/*
+ * Copyright © 2013 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#pragma once
+#ifndef MEMORY_WRITER_H
+#define MEMORY_WRITER_H
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+
+#ifdef __cplusplus
+/**
+ * Helper class for writing data to memory
+ *
+ * This class maintains a dynamically-sized memory buffer and allows
+ * for data to be efficiently appended to it with automatic resizing.
+ */
+class memory_writer
+{
+public:
+   memory_writer() :
+      memory(NULL),
+      curr_size(0),
+      pos(0) {}
+
+   ~memory_writer()
+   {
+      free(memory);
+   }
+
+   /* user wants to claim the memory */
+   char *release_memory(size_t *size)
+   {
+      /* final realloc to free allocated but unused memory */
+      char *result = (char *) realloc(memory, pos);
+      *size = pos;
+      memory = NULL;
+      curr_size = 0;
+      pos = 0;
+      return result;
+   }
+
+/**
+ * write functions per type
+ */
+#define DECL_WRITER(type) int write_ ##type (const type data) {\
+   return write(&data, sizeof(type));\
+}
+
+   DECL_WRITER(int32_t);
+   DECL_WRITER(int64_t);
+   DECL_WRITER(uint8_t);
+   DECL_WRITER(uint32_t);
+
+   int write_bool(bool data)
+   {
+      uint8_t val = data;
+      return write_uint8_t(val);
+   }
+
+   /* write function that reallocates more memory if required */
+   int write(const void *data, int32_t size)
+   {
+      if (!memory || pos > (int32_t)(curr_size - size))
+         if (grow(size))
+            return -1;
+
+      memcpy(memory + pos, data, size);
+
+      pos += size;
+      return 0;
+   }
+
+   int overwrite(const void *data, int32_t size, int32_t offset)
+   {
+      if (offset < 0 || offset + size > pos)
+         return -1;
+      memcpy(memory + offset, data, size);
+      return 0;
+   }
+
+   int write_string(const char *str)
+   {
+      if (!str)
+         return -1;
+      char terminator = '\0';
+      write(str, strlen(str));
+      write(&terminator, 1);
+      return 0;
+   }
+
+   inline int32_t position() { return pos; }
+
+
+private:
+
+   /* reallocate more memory */
+   int grow(int32_t size)
+   {
+      int32_t new_size = 2 * (curr_size + size);
+      char *more_mem = (char *) realloc(memory, new_size);
+      if (more_mem == NULL) {
+         free(memory);
+         memory = NULL;
+         return -1;
+      } else {
+         memory = more_mem;
+         curr_size = new_size;
+         return 0;
+      }
+   }
+
+   /* allocated memory */
+   char *memory;
+
+   /* current size of the whole allocation */
+   int32_t curr_size;
+
+   /* write position / size of the data written */
+   int32_t pos;
+};
+
+#endif /* ifdef __cplusplus */
+
+#endif /* MEMORY_WRITER_H */
-- 
1.8.3.1