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 <stdbool.h>
  33 #include <stddef.h>
  34 #include <stdint.h>
  35
  36 /* The blob functions implement a simple, low-level API for serializing and
  37  * deserializing.
  38  *
  39  * All objects written to a blob will be serialized directly, (without any
  40  * additional meta-data to describe the data written). Therefore, it is the
  41  * caller's responsibility to ensure that any data can be read later, (either
  42  * by knowing exactly what data is expected, or by writing to the blob
  43  * sufficient meta-data to describe what has been written).
  44  *
  45  * A blob is efficient in that it dynamically grows by doubling in size, so
  46  * allocation costs are logarithmic.
  47  */
  48
  49 struct blob {
  50    /* The data actually written to the blob. */
  51    uint8_t *data;
  52
  53    /** Number of bytes that have been allocated for \c data. */
  54    size_t allocated;
  55
  56    /** The number of bytes that have actual data written to them. */
  57    size_t size;
  58 };
  59
  60 /* When done reading, the caller can ensure that everything was consumed by
  61  * checking the following:
  62  *
  63  *   1. blob->current should be equal to blob->end, (if not, too little was
  64  *      read).
  65  *
  66  *   2. blob->overrun should be false, (otherwise, too much was read).
  67  */
  68 struct blob_reader {
  69    uint8_t *data;
  70    uint8_t *end;
  71    uint8_t *current;
  72    bool overrun;
  73 };
  74
  75 /**
  76  * Create a new, empty blob, belonging to \mem_ctx.
  77  *
  78  * \return The new blob, (or NULL in case of allocation failure).
  79  */
  80 struct blob *
  81 blob_create (void *mem_ctx);
  82
  83 /**
  84  * Add some unstructured, fixed-size data to a blob.
  85  *
  86  * \return True unless allocation failed.
  87  */
  88 bool
  89 blob_write_bytes (struct blob *blob, const void *bytes, size_t to_write);
  90
  91 /**
  92  * Reserve space in \blob for a number of bytes.
  93  *
  94  * Space will be allocated within the blob for these byes, but the bytes will
  95  * be left uninitialized. The caller is expected to use the return value to
  96  * write directly (and immediately) to these bytes.
  97  *
  98  * \note The return value is valid immediately upon return, but can be
  99  * invalidated by any other call to a blob function. So the caller should call
 100  * blob_reserve_byes immediately before writing through the returned pointer.
 101  *
 102  * This function is intended to be used when interfacing with an existing API
 103  * that is not aware of the blob API, (so that blob_write_bytes cannot be
 104  * called).
 105  *
 106  * \return A pointer to space allocated within \blob to which \to_write bytes
 107  * can be written, (or NULL in case of any allocation error).
 108  */
 109 uint8_t *
 110 blob_reserve_bytes (struct blob *blob, size_t to_write);
 111
 112 /**
 113  * Overwrite some data previously written to the blob.
 114  *
 115  * Writes data to an existing portion of the blob at an offset of \offset.
 116  * This data range must have previously been written to the blob by one of the
 117  * blob_write_* calls.
 118  *
 119  * For example usage, see blob_overwrite_uint32
 120  *
 121  * \return True unless the requested offset or offset+to_write lie outside
 122  * the current blob's size.
 123  */
 124 bool
 125 blob_overwrite_bytes (struct blob *blob,
 126                       size_t offset,
 127                       const void *bytes,
 128                       size_t to_write);
 129
 130 /**
 131  * Add a uint32_t to a blob.
 132  *
 133  * \note This function will only write to a uint32_t-aligned offset from the
 134  * beginning of the blob's data, so some padding bytes may be added to the
 135  * blob if this write follows some unaligned write (such as
 136  * blob_write_string).
 137  *
 138  * \return True unless allocation failed.
 139  */
 140 bool
 141 blob_write_uint32 (struct blob *blob, uint32_t value);
 142
 143 /**
 144  * Overwrite a uint32_t previously written to the blob.
 145  *
 146  * Writes a uint32_t value to an existing portion of the blob at an offset of
 147  * \offset.  This data range must have previously been written to the blob by
 148  * one of the blob_write_* calls.
 149  *
 150  *
 151  * The expected usage is something like the following pattern:
 152  *
 153  *      size_t offset;
 154  *
 155  *      offset = blob->size;
 156  *      blob_write_uint32 (blob, 0); // placeholder
 157  *      ... various blob write calls, writing N items ...
 158  *      blob_overwrite_uint32 (blob, offset, N);
 159  *
 160  * \return True unless the requested position or position+to_write lie outside
 161  * the current blob's size.
 162  */
 163 bool
 164 blob_overwrite_uint32 (struct blob *blob,
 165                        size_t offset,
 166                        uint32_t value);
 167
 168 /**
 169  * Add a uint64_t to a blob.
 170  *
 171  * \note This function will only write to a uint64_t-aligned offset from the
 172  * beginning of the blob's data, so some padding bytes may be added to the
 173  * blob if this write follows some unaligned write (such as
 174  * blob_write_string).
 175  *
 176  * \return True unless allocation failed.
 177  */
 178 bool
 179 blob_write_uint64 (struct blob *blob, uint64_t value);
 180
 181 /**
 182  * Add an intptr_t to a blob.
 183  *
 184  * \note This function will only write to an intptr_t-aligned offset from the
 185  * beginning of the blob's data, so some padding bytes may be added to the
 186  * blob if this write follows some unaligned write (such as
 187  * blob_write_string).
 188  *
 189  * \return True unless allocation failed.
 190  */
 191 bool
 192 blob_write_intptr (struct blob *blob, intptr_t value);
 193
 194 /**
 195  * Add a NULL-terminated string to a blob, (including the NULL terminator).
 196  *
 197  * \return True unless allocation failed.
 198  */
 199 bool
 200 blob_write_string (struct blob *blob, const char *str);
 201
 202 /**
 203  * Start reading a blob, (initializing the contents of \blob for reading).
 204  *
 205  * After this call, the caller can use the various blob_read_* functions to
 206  * read elements from the data array.
 207  *
 208  * For all of the blob_read_* functions, if there is insufficient data
 209  * remaining, the functions will do nothing, (perhaps returning default values
 210  * such as 0). The caller can detect this by noting that the blob_reader's
 211  * current value is unchanged before and after the call.
 212  */
 213 void
 214 blob_reader_init (struct blob_reader *blob, uint8_t *data, size_t size);
 215
 216 /**
 217  * Read some unstructured, fixed-size data from the current location, (and
 218  * update the current location to just past this data).
 219  *
 220  * \note The memory returned belongs to the data underlying the blob reader. The
 221  * caller must copy the data in order to use it after the lifetime of the data
 222  * underlying the blob reader.
 223  *
 224  * \return The bytes read (see note above about memory lifetime).
 225  */
 226 void *
 227 blob_read_bytes (struct blob_reader *blob, size_t size);
 228
 229 /**
 230  * Read some unstructured, fixed-size data from the current location, copying
 231  * it to \dest (and update the current location to just past this data)
 232  */
 233 void
 234 blob_copy_bytes (struct blob_reader *blob, uint8_t *dest, size_t size);
 235
 236 /**
 237  * Read a uint32_t from the current location, (and update the current location
 238  * to just past this uint32_t).
 239  *
 240  * \note This function will only read from a uint32_t-aligned offset from the
 241  * beginning of the blob's data, so some padding bytes may be skipped.
 242  *
 243  * \return The uint32_t read
 244  */
 245 uint32_t
 246 blob_read_uint32 (struct blob_reader *blob);
 247
 248 /**
 249  * Read a uint64_t from the current location, (and update the current location
 250  * to just past this uint64_t).
 251  *
 252  * \note This function will only read from a uint64_t-aligned offset from the
 253  * beginning of the blob's data, so some padding bytes may be skipped.
 254  *
 255  * \return The uint64_t read
 256  */
 257 uint64_t
 258 blob_read_uint64 (struct blob_reader *blob);
 259
 260 /**
 261  * Read an intptr_t value from the current location, (and update the
 262  * current location to just past this intptr_t).
 263  *
 264  * \note This function will only read from an intptr_t-aligned offset from the
 265  * beginning of the blob's data, so some padding bytes may be skipped.
 266  *
 267  * \return The intptr_t read
 268  */
 269 intptr_t
 270 blob_read_intptr (struct blob_reader *blob);
 271
 272 /**
 273  * Read a NULL-terminated string from the current location, (and update the
 274  * current location to just past this string).
 275  *
 276  * \note The memory returned belongs to the data underlying the blob reader. The
 277  * caller must copy the string in order to use the string after the lifetime
 278  * of the data underlying the blob reader.
 279  *
 280  * \return The string read (see note above about memory lifetime). However, if
 281  * there is no NULL byte remaining within the blob, this function returns
 282  * NULL.
 283  */
 284 char *
 285 blob_read_string (struct blob_reader *blob);
 286
 287 #ifdef __cplusplus
 288 }
 289 #endif
 290
 291 #endif /* BLOB_H */