[Mesa-dev] [PATCH 03/10] glsl: memory_map helper class for data deserialization

[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_map.h | 171 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 171 insertions(+)
 create mode 100644 src/glsl/memory_map.h

diff --git a/src/glsl/memory_map.h b/src/glsl/memory_map.h
new file mode 100644
index 0000000..dbfa48e
--- /dev/null
+++ b/src/glsl/memory_map.h
@@ -0,0 +1,171 @@
+/* -*- 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_MAP_H
+#define MEMORY_MAP_H
+
+#include <stdint.h>
+#include <string.h>
+#include "ralloc.h"
+
+#ifdef __cplusplus
+
+/**
+ * Helper class to read data
+ *
+ * Class reads data from user given memory.
+ */
+class memory_map
+{
+public:
+   memory_map() :
+      error(false),
+      cache_size(0),
+      cache_mmap(NULL),
+      cache_mmap_p(NULL)
+   {
+      /* only used by read_string() */
+      mem_ctx = ralloc_context(NULL);
+   }
+
+   /* read from memory */
+   void map(const void *memory, size_t size)
+   {
+      cache_mmap_p = cache_mmap = (char *) memory;
+      cache_size = size;
+   }
+
+   /* wrap a portion from another map */
+   void map(memory_map &map, size_t size)
+   {
+      cache_mmap_p = cache_mmap = map.cache_mmap_p;
+      cache_size = size;
+      map.ffwd(size);
+   }
+
+   ~memory_map() {
+      ralloc_free(mem_ctx);
+   }
+
+   /* move read pointer forward */
+   inline void ffwd(int len)
+   {
+      cache_mmap_p += len;
+   }
+
+   inline void jump(unsigned pos)
+   {
+      cache_mmap_p = cache_mmap + pos;
+   }
+
+   /**
+    * safety check to avoid reading over cache_size,
+    * returns bool if it is safe to continue reading
+    */
+   bool safe_read(unsigned size)
+   {
+      if (position() + size > cache_size)
+         error = true;
+      return !error;
+   }
+
+   /* position of read pointer */
+   inline uint32_t position()
+   {
+      return cache_mmap_p - cache_mmap;
+   }
+
+   inline char *read_string()
+   {
+      uint32_t len = read_uint32_t();
+
+      /* NULL pointer is supported */
+      if (len == 0)
+         return NULL;
+
+      /* verify that string is terminated after reported length */
+      if (*(cache_mmap_p + len) != '\0') {
+         error = true;
+         return NULL;
+      }
+
+      char *str = ralloc_strdup(mem_ctx, cache_mmap_p);
+      ffwd(len+1);
+      return str;
+   }
+
+/**
+ * read functions per type
+ */
+#define DECL_READER(type) type read_ ##type () {\
+   if (!safe_read(sizeof(type)))\
+      return 0;\
+   ffwd(sizeof(type));\
+   return *(type *) (cache_mmap_p - sizeof(type));\
+}
+
+   DECL_READER(int32_t);
+   DECL_READER(int64_t);
+   DECL_READER(uint8_t);
+   DECL_READER(uint32_t);
+
+   inline uint8_t read_bool()
+   {
+      return read_uint8_t();
+   }
+
+   inline void read(void *dst, size_t size)
+   {
+      if (!safe_read(size))
+         return;
+      memcpy(dst, cache_mmap_p, size);
+      ffwd(size);
+   }
+
+   /* total size of mapped memory */
+   inline int32_t size()
+   {
+      return cache_size;
+   }
+
+   inline bool errors()
+   {
+      return error;
+   }
+
+private:
+
+   void *mem_ctx;
+
+   /* if errors have occured during reading */
+   bool error;
+
+   unsigned cache_size;
+   char *cache_mmap;
+   char *cache_mmap_p;
+};
+#endif /* ifdef __cplusplus */
+
+#endif /* MEMORY_MAP_H */
-- 
1.8.5.3