src/compiler/glsl/blob.h

   1 /*
   2  * Copyright © 2014 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  */
  23
  24 #pragma once
  25 #ifndef BLOB_H
  26 #define BLOB_H
  27
  28 #ifdef __cplusplus
  29 extern "C" {
  30 #endif
  31
  32 #include <stdint.h>
  33
  34 /* The blob functions implement a simple, low-level API for serializing and
  35  * deserializing.
  36  *
  37  * All objects written to a blob will be serialized directly, (without any
  38  * additional meta-data to describe the data written). Therefore, it is the
  39  * caller's responsibility to ensure that any data can be read later, (either
  40  * by knowing exactly what data is expected, or by writing to the blob
  41  * sufficient meta-data to describe what has been written).
  42  *
  43  * A blob is efficient in that it dynamically grows by doubling in size, so
  44  * allocation costs are logarithmic.
  45  */
  46
  47 struct blob {
  48    /* The data actually written to the blob. */
  49    uint8_t *data;
  50
  51    /** Number of bytes that have been allocated for \c data. */
  52    size_t allocated;
  53
  54    /** The number of bytes that have actual data written to them. */
  55    size_t size;
  56 };
  57
  58 /* When done reading, the caller can ensure that everything was consumed by
  59  * checking the following:
  60  *
  61  *   1. blob->current should be equal to blob->end, (if not, too little was
  62  *      read).
  63  *
  64  *   2. blob->overrun should be false, (otherwise, too much was read).
  65  */
  66 struct blob_reader {
  67    uint8_t *data;
  68    uint8_t *end;
  69    uint8_t *current;
  70    bool overrun;
  71 };
  72
  73 /**
  74  * Create a new, empty blob, belonging to \mem_ctx.
  75  *
  76  * \return The new blob, (or NULL in case of allocation failure).
  77  */
  78 struct blob *
  79 blob_create (void *mem_ctx);
  80
  81 /**
  82  * Add some unstructured, fixed-size data to a blob.
  83  *
  84  * \return True unless allocation failed.
  85  */
  86 bool
  87 blob_write_bytes (struct blob *blob, const void *bytes, size_t to_write);
  88
  89 /**
  90  * Reserve space in \blob for a number of bytes.
  91  *
  92  * Space will be allocated within the blob for these byes, but the bytes will
  93  * be left uninitialized. The caller is expected to use the return value to
  94  * write directly (and immediately) to these bytes.
  95  *
  96  * \note The return value is valid immediately upon return, but can be
  97  * invalidated by any other call to a blob function. So the caller should call
  98  * blob_reserve_byes immediately before writing through the returned pointer.
  99  *
 100  * This function is intended to be used when interfacing with an existing API
 101  * that is not aware of the blob API, (so that blob_write_bytes cannot be
 102  * called).
 103  *
 104  * \return A pointer to space allocated within \blob to which \to_write bytes
 105  * can be written, (or NULL in case of any allocation error).
 106  */
 107 uint8_t *
 108 blob_reserve_bytes (struct blob *blob, size_t to_write);
 109
 110 /**
 111  * Overwrite some data previously written to the blob.
 112  *
 113  * Writes data to an existing portion of the blob at an offset of \offset.
 114  * This data range must have previously been written to the blob by one of the
 115  * blob_write_* calls.
 116  *
 117  * For example usage, see blob_overwrite_uint32
 118  *
 119  * \return True unless the requested offset or offset+to_write lie outside
 120  * the current blob's size.
 121  */
 122 bool
 123 blob_overwrite_bytes (struct blob *blob,
 124                       size_t offset,
 125                       const void *bytes,
 126                       size_t to_write);
 127
 128 /**
 129  * Add a uint32_t to a blob.
 130  *
 131  * \note This function will only write to a uint32_t-aligned offset from the
 132  * beginning of the blob's data, so some padding bytes may be added to the
 133  * blob if this write follows some unaligned write (such as
 134  * blob_write_string).
 135  *
 136  * \return True unless allocation failed.
 137  */
 138 bool
 139 blob_write_uint32 (struct blob *blob, uint32_t value);
 140
 141 /**
 142  * Overwrite a uint32_t previously written to the blob.
 143  *
 144  * Writes a uint32_t value to an existing portion of the blob at an offset of
 145  * \offset.  This data range must have previously been written to the blob by
 146  * one of the blob_write_* calls.
 147  *
 148  *
 149  * The expected usage is something like the following pattern:
 150  *
 151  *      size_t offset;
 152  *
 153  *      offset = blob->size;
 154  *      blob_write_uint32 (blob, 0); // placeholder
 155  *      ... various blob write calls, writing N items ...
 156  *      blob_overwrite_uint32 (blob, offset, N);
 157  *
 158  * \return True unless the requested position or position+to_write lie outside
 159  * the current blob's size.
 160  */
 161 bool
 162 blob_overwrite_uint32 (struct blob *blob,
 163                        size_t offset,
 164                        uint32_t value);
 165
 166 /**
 167  * Add a uint64_t to a blob.
 168  *
 169  * \note This function will only write to a uint64_t-aligned offset from the
 170  * beginning of the blob's data, so some padding bytes may be added to the
 171  * blob if this write follows some unaligned write (such as
 172  * blob_write_string).
 173  *
 174  * \return True unless allocation failed.
 175  */
 176 bool
 177 blob_write_uint64 (struct blob *blob, uint64_t value);
 178
 179 /**
 180  * Add an intptr_t to a blob.
 181  *
 182  * \note This function will only write to an intptr_t-aligned offset from the
 183  * beginning of the blob's data, so some padding bytes may be added to the
 184  * blob if this write follows some unaligned write (such as
 185  * blob_write_string).
 186  *
 187  * \return True unless allocation failed.
 188  */
 189 bool
 190 blob_write_intptr (struct blob *blob, intptr_t value);
 191
 192 /**
 193  * Add a NULL-terminated string to a blob, (including the NULL terminator).
 194  *
 195  * \return True unless allocation failed.
 196  */
 197 bool
 198 blob_write_string (struct blob *blob, const char *str);
 199
 200 /**
 201  * Start reading a blob, (initializing the contents of \blob for reading).
 202  *
 203  * After this call, the caller can use the various blob_read_* functions to
 204  * read elements from the data array.
 205  *
 206  * For all of the blob_read_* functions, if there is insufficient data
 207  * remaining, the functions will do nothing, (perhaps returning default values
 208  * such as 0). The caller can detect this by noting that the blob_reader's
 209  * current value is unchanged before and after the call.
 210  */
 211 void
 212 blob_reader_init (struct blob_reader *blob, uint8_t *data, size_t size);
 213
 214 /**
 215  * Read some unstructured, fixed-size data from the current location, (and
 216  * update the current location to just past this data).
 217  *
 218  * \note The memory returned belongs to the data underlying the blob reader. The
 219  * caller must copy the data in order to use it after the lifetime of the data
 220  * underlying the blob reader.
 221  *
 222  * \return The bytes read (see note above about memory lifetime).
 223  */
 224 void *
 225 blob_read_bytes (struct blob_reader *blob, size_t size);
 226
 227 /**
 228  * Read some unstructured, fixed-size data from the current location, copying
 229  * it to \dest (and update the current location to just past this data)
 230  */
 231 void
 232 blob_copy_bytes (struct blob_reader *blob, uint8_t *dest, size_t size);
 233
 234 /**
 235  * Read a uint32_t from the current location, (and update the current location
 236  * to just past this uint32_t).
 237  *
 238  * \note This function will only read from a uint32_t-aligned offset from the
 239  * beginning of the blob's data, so some padding bytes may be skipped.
 240  *
 241  * \return The uint32_t read
 242  */
 243 uint32_t
 244 blob_read_uint32 (struct blob_reader *blob);
 245
 246 /**
 247  * Read a uint64_t from the current location, (and update the current location
 248  * to just past this uint64_t).
 249  *
 250  * \note This function will only read from a uint64_t-aligned offset from the
 251  * beginning of the blob's data, so some padding bytes may be skipped.
 252  *
 253  * \return The uint64_t read
 254  */
 255 uint64_t
 256 blob_read_uint64 (struct blob_reader *blob);
 257
 258 /**
 259  * Read an intptr_t value from the current location, (and update the
 260  * current location to just past this intptr_t).
 261  *
 262  * \note This function will only read from an intptr_t-aligned offset from the
 263  * beginning of the blob's data, so some padding bytes may be skipped.
 264  *
 265  * \return The intptr_t read
 266  */
 267 intptr_t
 268 blob_read_intptr (struct blob_reader *blob);
 269
 270 /**
 271  * Read a NULL-terminated string from the current location, (and update the
 272  * current location to just past this string).
 273  *
 274  * \note The memory returned belongs to the data underlying the blob reader. The
 275  * caller must copy the string in order to use the string after the lifetime
 276  * of the data underlying the blob reader.
 277  *
 278  * \return The string read (see note above about memory lifetime). However, if
 279  * there is no NULL byte remaining within the blob, this function returns
 280  * NULL.
 281  */
 282 char *
 283 blob_read_string (struct blob_reader *blob);
 284
 285 #ifdef __cplusplus
 286 }
 287 #endif
 288
 289 #endif /* BLOB_H */