[Mesa-dev] [wip 3/9] 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 | 174 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 174 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..1b68b72
--- /dev/null
+++ b/src/glsl/memory_map.h
@@ -0,0 +1,174 @@
+/* -*- 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 <fcntl.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+
+#ifdef __cplusplus
+
+/**
+ * Helper class to read data
+ *
+ * Class can read either from user given memory or from a file. On Linux
+ * file reading wraps around the Posix functions for mapping a file into
+ * the process's address space. Other OS may need different implementation.
+ */
+class memory_map
+{
+public:
+   memory_map() :
+      mode(memory_map::READ_MEM),
+      fd(0),
+      cache_size(0),
+      cache_mmap(NULL),
+      cache_mmap_p(NULL)
+   {
+      /* only used by read_string() */
+      mem_ctx = ralloc_context(NULL);
+   }
+
+   /* read from disk */
+   int map(const char *path)
+   {
+      struct stat stat_info;
+      if (stat(path, &stat_info) != 0)
+         return -1;
+
+      mode = memory_map::READ_MAP;
+      cache_size = stat_info.st_size;
+
+      fd = open(path, O_RDONLY);
+      if (fd) {
+         cache_mmap_p = cache_mmap = (char *)
+            mmap(NULL, cache_size, PROT_READ, MAP_PRIVATE, fd, 0);
+         return (cache_mmap == MAP_FAILED) ? -1 : 0;
+      }
+      return -1;
+   }
+
+   /* read from memory */
+   int map(const void *memory, size_t size)
+   {
+      cache_mmap_p = cache_mmap = (char *) memory;
+      cache_size = size;
+      return 0;
+   }
+
+   /* wrap a portion from another map */
+   int map(memory_map &map, size_t size)
+   {
+      cache_mmap_p = cache_mmap = map.cache_mmap_p;
+      cache_size = size;
+      map.ffwd(size);
+      return 0;
+   }
+
+   ~memory_map() {
+      if (cache_mmap && mode == READ_MAP) {
+         munmap(cache_mmap, cache_size);
+         close(fd);
+      }
+      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;
+   }
+
+
+   /* position of read pointer */
+   inline uint32_t position()
+   {
+      return cache_mmap_p - cache_mmap;
+   }
+
+   inline char *read_string()
+   {
+      char *str = ralloc_strdup(mem_ctx, cache_mmap_p);
+      ffwd(strlen(str)+1);
+      return str;
+   }
+
+/**
+ * read functions per type
+ */
+#define DECL_READER(type) type read_ ##type () {\
+   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)
+   {
+      memcpy(dst, cache_mmap_p, size);
+      ffwd(size);
+   }
+
+   /* total size of mapped memory */
+   inline int32_t size()
+   {
+      return cache_size;
+   }
+
+private:
+
+   void *mem_ctx;
+
+   /* specifies if we are reading mapped memory or user passed mem */
+   enum read_mode {
+      READ_MEM = 0,
+      READ_MAP
+   };
+
+   int32_t mode;
+   int32_t fd;
+   int32_t cache_size;
+   char *cache_mmap;
+   char *cache_mmap_p;
+};
+#endif /* ifdef __cplusplus */
+
+#endif /* MEMORY_MAP_H */
-- 
1.8.3.1