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 #ifndef BLOB_H
  25 #define BLOB_H
  26
  27 #include <stdbool.h>
  28 #include <stddef.h>
  29 #include <stdint.h>
  30 #include <stdlib.h>
  31
  32 #ifdef __cplusplus
  33 extern "C" {
  34 #endif
  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.
  77  *
  78  * \return The new blob, (or NULL in case of allocation failure).
  79  */
  80 struct blob *
  81 blob_create(void);
  82
  83 /**
  84  * Destroy a blob and free its memory.
  85  */
  86 static inline void
  87 blob_destroy(struct blob *blob)
  88 {
  89    free(blob->data);
  90    free(blob);
  91 }
  92
  93 /**
  94  * Add some unstructured, fixed-size data to a blob.
  95  *
  96  * \return True unless allocation failed.
  97  */
  98 bool
  99 blob_write_bytes(struct blob *blob, const void *bytes, size_t to_write);
 100
 101 /**
 102  * Reserve space in \blob for a number of bytes.
 103  *
 104  * Space will be allocated within the blob for these byes, but the bytes will
 105  * be left uninitialized. The caller is expected to use the return value to
 106  * write directly (and immediately) to these bytes.
 107  *
 108  * \note The return value is valid immediately upon return, but can be
 109  * invalidated by any other call to a blob function. So the caller should call
 110  * blob_reserve_byes immediately before writing through the returned pointer.
 111  *
 112  * This function is intended to be used when interfacing with an existing API
 113  * that is not aware of the blob API, (so that blob_write_bytes cannot be
 114  * called).
 115  *
 116  * \return A pointer to space allocated within \blob to which \to_write bytes
 117  * can be written, (or NULL in case of any allocation error).
 118  */
 119 uint8_t *
 120 blob_reserve_bytes(struct blob *blob, size_t to_write);
 121
 122 /**
 123  * Overwrite some data previously written to the blob.
 124  *
 125  * Writes data to an existing portion of the blob at an offset of \offset.
 126  * This data range must have previously been written to the blob by one of the
 127  * blob_write_* calls.
 128  *
 129  * For example usage, see blob_overwrite_uint32
 130  *
 131  * \return True unless the requested offset or offset+to_write lie outside
 132  * the current blob's size.
 133  */
 134 bool
 135 blob_overwrite_bytes(struct blob *blob,
 136                      size_t offset,
 137                      const void *bytes,
 138                      size_t to_write);
 139
 140 /**
 141  * Add a uint32_t to a blob.
 142  *
 143  * \note This function will only write to a uint32_t-aligned offset from the
 144  * beginning of the blob's data, so some padding bytes may be added to the
 145  * blob if this write follows some unaligned write (such as
 146  * blob_write_string).
 147  *
 148  * \return True unless allocation failed.
 149  */
 150 bool
 151 blob_write_uint32(struct blob *blob, uint32_t value);
 152
 153 /**
 154  * Overwrite a uint32_t previously written to the blob.
 155  *
 156  * Writes a uint32_t value to an existing portion of the blob at an offset of
 157  * \offset.  This data range must have previously been written to the blob by
 158  * one of the blob_write_* calls.
 159  *
 160  *
 161  * The expected usage is something like the following pattern:
 162  *
 163  *      size_t offset;
 164  *
 165  *      offset = blob->size;
 166  *      blob_write_uint32 (blob, 0); // placeholder
 167  *      ... various blob write calls, writing N items ...
 168  *      blob_overwrite_uint32 (blob, offset, N);
 169  *
 170  * \return True unless the requested position or position+to_write lie outside
 171  * the current blob's size.
 172  */
 173 bool
 174 blob_overwrite_uint32(struct blob *blob,
 175                       size_t offset,
 176                       uint32_t value);
 177
 178 /**
 179  * Add a uint64_t to a blob.
 180  *
 181  * \note This function will only write to a uint64_t-aligned offset from the
 182  * beginning of the blob's data, so some padding bytes may be added to the
 183  * blob if this write follows some unaligned write (such as
 184  * blob_write_string).
 185  *
 186  * \return True unless allocation failed.
 187  */
 188 bool
 189 blob_write_uint64(struct blob *blob, uint64_t value);
 190
 191 /**
 192  * Add an intptr_t to a blob.
 193  *
 194  * \note This function will only write to an intptr_t-aligned offset from the
 195  * beginning of the blob's data, so some padding bytes may be added to the
 196  * blob if this write follows some unaligned write (such as
 197  * blob_write_string).
 198  *
 199  * \return True unless allocation failed.
 200  */
 201 bool
 202 blob_write_intptr(struct blob *blob, intptr_t value);
 203
 204 /**
 205  * Add a NULL-terminated string to a blob, (including the NULL terminator).
 206  *
 207  * \return True unless allocation failed.
 208  */
 209 bool
 210 blob_write_string(struct blob *blob, const char *str);
 211
 212 /**
 213  * Start reading a blob, (initializing the contents of \blob for reading).
 214  *
 215  * After this call, the caller can use the various blob_read_* functions to
 216  * read elements from the data array.
 217  *
 218  * For all of the blob_read_* functions, if there is insufficient data
 219  * remaining, the functions will do nothing, (perhaps returning default values
 220  * such as 0). The caller can detect this by noting that the blob_reader's
 221  * current value is unchanged before and after the call.
 222  */
 223 void
 224 blob_reader_init(struct blob_reader *blob, uint8_t *data, size_t size);
 225
 226 /**
 227  * Read some unstructured, fixed-size data from the current location, (and
 228  * update the current location to just past this data).
 229  *
 230  * \note The memory returned belongs to the data underlying the blob reader. The
 231  * caller must copy the data in order to use it after the lifetime of the data
 232  * underlying the blob reader.
 233  *
 234  * \return The bytes read (see note above about memory lifetime).
 235  */
 236 void *
 237 blob_read_bytes(struct blob_reader *blob, size_t size);
 238
 239 /**
 240  * Read some unstructured, fixed-size data from the current location, copying
 241  * it to \dest (and update the current location to just past this data)
 242  */
 243 void
 244 blob_copy_bytes(struct blob_reader *blob, uint8_t *dest, size_t size);
 245
 246 /**
 247  * Read a uint32_t from the current location, (and update the current location
 248  * to just past this uint32_t).
 249  *
 250  * \note This function will only read from a uint32_t-aligned offset from the
 251  * beginning of the blob's data, so some padding bytes may be skipped.
 252  *
 253  * \return The uint32_t read
 254  */
 255 uint32_t
 256 blob_read_uint32(struct blob_reader *blob);
 257
 258 /**
 259  * Read a uint64_t from the current location, (and update the current location
 260  * to just past this uint64_t).
 261  *
 262  * \note This function will only read from a uint64_t-aligned offset from the
 263  * beginning of the blob's data, so some padding bytes may be skipped.
 264  *
 265  * \return The uint64_t read
 266  */
 267 uint64_t
 268 blob_read_uint64(struct blob_reader *blob);
 269
 270 /**
 271  * Read an intptr_t value from the current location, (and update the
 272  * current location to just past this intptr_t).
 273  *
 274  * \note This function will only read from an intptr_t-aligned offset from the
 275  * beginning of the blob's data, so some padding bytes may be skipped.
 276  *
 277  * \return The intptr_t read
 278  */
 279 intptr_t
 280 blob_read_intptr(struct blob_reader *blob);
 281
 282 /**
 283  * Read a NULL-terminated string from the current location, (and update the
 284  * current location to just past this string).
 285  *
 286  * \note The memory returned belongs to the data underlying the blob reader. The
 287  * caller must copy the string in order to use the string after the lifetime
 288  * of the data underlying the blob reader.
 289  *
 290  * \return The string read (see note above about memory lifetime). However, if
 291  * there is no NULL byte remaining within the blob, this function returns
 292  * NULL.
 293  */
 294 char *
 295 blob_read_string(struct blob_reader *blob);
 296
 297 #ifdef __cplusplus
 298 }
 299 #endif
 300
 301 #endif /* BLOB_H */