ucx: src/buffer.c@3390b58ad15a

     1 /*

     2  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

     3  *

     4  * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.

     5  *

     6  * Redistribution and use in source and binary forms, with or without

     7  * modification, are permitted provided that the following conditions are met:

     8  *

     9  *   1. Redistributions of source code must retain the above copyright

    10  *      notice, this list of conditions and the following disclaimer.

    11  *

    12  *   2. Redistributions in binary form must reproduce the above copyright

    13  *      notice, this list of conditions and the following disclaimer in the

    14  *      documentation and/or other materials provided with the distribution.

    15  *

    16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

    17  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

    18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

    19  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE

    20  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

    21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

    22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

    23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

    24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

    25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

    26  * POSSIBILITY OF SUCH DAMAGE.

    27  */

    29 #include "cx/buffer.h"

    30 #include "cx/utils.h"

    32 #include <stdio.h>

    33 #include <string.h>

    35 int cxBufferInit(

    36         CxBuffer *buffer,

    37         void *space,

    38         size_t capacity,

    39         CxAllocator const *allocator,

    40         int flags

    41 ) {

    42     if (allocator == NULL) allocator = cxDefaultAllocator;

    43     buffer->allocator = allocator;

    44     buffer->flags = flags;

    45     if (!space) {

    46         buffer->bytes = cxMalloc(allocator, capacity);

    47         if (buffer->bytes == NULL) {

    48             return 1;

    49         }

    50         buffer->flags |= CX_BUFFER_FREE_CONTENTS;

    51     } else {

    52         buffer->bytes = space;

    53     }

    54     buffer->capacity = capacity;

    55     buffer->size = 0;

    56     buffer->pos = 0;

    58     buffer->flush_func = NULL;

    59     buffer->flush_target = NULL;

    60     buffer->flush_blkmax = 0;

    61     buffer->flush_blksize = 4096;

    62     buffer->flush_threshold = SIZE_MAX;

    64     return 0;

    65 }

    67 void cxBufferDestroy(CxBuffer *buffer) {

    68     if ((buffer->flags & CX_BUFFER_FREE_CONTENTS) == CX_BUFFER_FREE_CONTENTS) {

    69         cxFree(buffer->allocator, buffer->bytes);

    70     }

    71 }

    73 CxBuffer *cxBufferCreate(

    74         void *space,

    75         size_t capacity,

    76         CxAllocator const *allocator,

    77         int flags

    78 ) {

    79     CxBuffer *buf = cxMalloc(allocator, sizeof(CxBuffer));

    80     if (buf == NULL) return NULL;

    81     if (0 == cxBufferInit(buf, space, capacity, allocator, flags)) {

    82         return buf;

    83     } else {

    84         cxFree(allocator, buf);

    85         return NULL;

    86     }

    87 }

    89 void cxBufferFree(CxBuffer *buffer) {

    90     if ((buffer->flags & CX_BUFFER_FREE_CONTENTS) == CX_BUFFER_FREE_CONTENTS) {

    91         cxFree(buffer->allocator, buffer->bytes);

    92     }

    93     cxFree(buffer->allocator, buffer);

    94 }

    96 int cxBufferSeek(

    97         CxBuffer *buffer,

    98         off_t offset,

    99         int whence

   100 ) {

   101     size_t npos;

   102     switch (whence) {

   103         case SEEK_CUR:

   104             npos = buffer->pos;

   105             break;

   106         case SEEK_END:

   107             npos = buffer->size;

   108             break;

   109         case SEEK_SET:

   110             npos = 0;

   111             break;

   112         default:

   113             return -1;

   114     }

   116     size_t opos = npos;

   117     npos += offset;

   119     if ((offset > 0 && npos < opos) || (offset < 0 && npos > opos)) {

   120         return -1;

   121     }

   123     if (npos >= buffer->size) {

   124         return -1;

   125     } else {

   126         buffer->pos = npos;

   127         return 0;

   128     }

   130 }

   132 void cxBufferClear(CxBuffer *buffer) {

   133     memset(buffer->bytes, 0, buffer->size);

   134     buffer->size = 0;

   135     buffer->pos = 0;

   136 }

   138 int cxBufferEof(CxBuffer const *buffer) {

   139     return buffer->pos >= buffer->size;

   140 }

   142 int cxBufferMinimumCapacity(

   143         CxBuffer *buffer,

   144         size_t newcap

   145 ) {

   146     if (newcap <= buffer->capacity) {

   147         return 0;

   148     }

   150     if (cxReallocate(buffer->allocator,

   151                      (void **) &buffer->bytes, newcap) == 0) {

   152         buffer->capacity = newcap;

   153         return 0;

   154     } else {

   155         return -1;

   156     }

   157 }

   159 /**

   160  * Helps flushing data to the flush target of a buffer.

   161  *

   162  * @param buffer the buffer containing the config

   163  * @param space the data to flush

   164  * @param size the element size

   165  * @param nitems the number of items

   166  * @return the number of items flushed

   167  */

   168 static size_t cx_buffer_write_flush_helper(

   169         CxBuffer *buffer,

   170         unsigned char const *space,

   171         size_t size,

   172         size_t nitems

   173 ) {

   174     size_t pos = 0;

   175     size_t remaining = nitems;

   176     size_t max_items = buffer->flush_blksize / size;

   177     while (remaining > 0) {

   178         size_t items = remaining > max_items ? max_items : remaining;

   179         size_t flushed = buffer->flush_func(

   180                 space + pos,

   181                 size, items,

   182                 buffer->flush_target);

   183         if (flushed > 0) {

   184             pos += (flushed * size);

   185             remaining -= flushed;

   186         } else {

   187             // if no bytes can be flushed out anymore, we give up

   188             break;

   189         }

   190     }

   191     return nitems - remaining;

   192 }

   194 size_t cxBufferWrite(

   195         void const *ptr,

   196         size_t size,

   197         size_t nitems,

   198         CxBuffer *buffer

   199 ) {

   200     // optimize for easy case

   201     if (size == 1 && (buffer->capacity - buffer->pos) >= nitems) {

   202         memcpy(buffer->bytes + buffer->pos, ptr, nitems);

   203         buffer->pos += nitems;

   204         if (buffer->pos > buffer->size) {

   205             buffer->size = buffer->pos;

   206         }

   207         return nitems;

   208     }

   210     size_t len;

   211     size_t nitems_out = nitems;

   212     if (cx_szmul(size, nitems, &len)) {

   213         return 0;

   214     }

   215     size_t required = buffer->pos + len;

   216     if (buffer->pos > required) {

   217         return 0;

   218     }

   220     bool perform_flush = false;

   221     if (required > buffer->capacity) {

   222         if ((buffer->flags & CX_BUFFER_AUTO_EXTEND) == CX_BUFFER_AUTO_EXTEND && required) {

   223             if (buffer->flush_blkmax > 0 && required > buffer->flush_threshold) {

   224                 perform_flush = true;

   225             } else {

   226                 if (cxBufferMinimumCapacity(buffer, required)) {

   227                     return 0;

   228                 }

   229             }

   230         } else {

   231             if (buffer->flush_blkmax > 0) {

   232                 perform_flush = true;

   233             } else {

   234                 // truncate data to be written, if we can neither extend nor flush

   235                 len = buffer->capacity - buffer->pos;

   236                 if (size > 1) {

   237                     len -= len % size;

   238                 }

   239                 nitems_out = len / size;

   240             }

   241         }

   242     }

   244     if (len == 0) {

   245         return len;

   246     }

   248     if (perform_flush) {

   249         size_t flush_max;

   250         if (cx_szmul(buffer->flush_blkmax, buffer->flush_blksize, &flush_max)) {

   251             return 0;

   252         }

   253         size_t flush_pos = buffer->flush_func == NULL || buffer->flush_target == NULL

   254                            ? buffer->pos

   255                            : cx_buffer_write_flush_helper(buffer, buffer->bytes, 1, buffer->pos);

   256         if (flush_pos == buffer->pos) {

   257             // entire buffer has been flushed, we can reset

   258             buffer->size = buffer->pos = 0;

   260             size_t items_flush; // how many items can also be directly flushed

   261             size_t items_keep; // how many items have to be written to the buffer

   263             items_flush = flush_max >= required ? nitems : (flush_max - flush_pos) / size;

   264             if (items_flush > 0) {

   265                 items_flush = cx_buffer_write_flush_helper(buffer, ptr, size, items_flush / size);

   266                 // in case we could not flush everything, keep the rest

   267             }

   268             items_keep = nitems - items_flush;

   269             if (items_keep > 0) {

   270                 // try again with the remaining stuff

   271                 unsigned char const *new_ptr = ptr;

   272                 new_ptr += items_flush * size;

   273                 // report the directly flushed items as written plus the remaining stuff

   274                 return items_flush + cxBufferWrite(new_ptr, size, items_keep, buffer);

   275             } else {

   276                 // all items have been flushed - report them as written

   277                 return nitems;

   278             }

   279         } else if (flush_pos == 0) {

   280             // nothing could be flushed at all, we immediately give up without writing any data

   281             return 0;

   282         } else {

   283             // we were partially successful, we shift left and try again

   284             cxBufferShiftLeft(buffer, flush_pos);

   285             return cxBufferWrite(ptr, size, nitems, buffer);

   286         }

   287     } else {

   288         memcpy(buffer->bytes + buffer->pos, ptr, len);

   289         buffer->pos += len;

   290         if (buffer->pos > buffer->size) {

   291             buffer->size = buffer->pos;

   292         }

   293         return nitems_out;

   294     }

   296 }

   298 int cxBufferPut(

   299         CxBuffer *buffer,

   300         int c

   301 ) {

   302     c &= 0xFF;

   303     unsigned char const ch = c;

   304     if (cxBufferWrite(&ch, 1, 1, buffer) == 1) {

   305         return c;

   306     } else {

   307         return EOF;

   308     }

   309 }

   311 size_t cxBufferPutString(

   312         CxBuffer *buffer,

   313         const char *str

   314 ) {

   315     return cxBufferWrite(str, 1, strlen(str), buffer);

   316 }

   318 size_t cxBufferRead(

   319         void *ptr,

   320         size_t size,

   321         size_t nitems,

   322         CxBuffer *buffer

   323 ) {

   324     size_t len;

   325     if (cx_szmul(size, nitems, &len)) {

   326         return 0;

   327     }

   328     if (buffer->pos + len > buffer->size) {

   329         len = buffer->size - buffer->pos;

   330         if (size > 1) len -= len % size;

   331     }

   333     if (len <= 0) {

   334         return len;

   335     }

   337     memcpy(ptr, buffer->bytes + buffer->pos, len);

   338     buffer->pos += len;

   340     return len / size;

   341 }

   343 int cxBufferGet(CxBuffer *buffer) {

   344     if (cxBufferEof(buffer)) {

   345         return EOF;

   346     } else {

   347         int c = buffer->bytes[buffer->pos];

   348         buffer->pos++;

   349         return c;

   350     }

   351 }

   353 int cxBufferShiftLeft(

   354         CxBuffer *buffer,

   355         size_t shift

   356 ) {

   357     if (shift >= buffer->size) {

   358         buffer->pos = buffer->size = 0;

   359     } else {

   360         memmove(buffer->bytes, buffer->bytes + shift, buffer->size - shift);

   361         buffer->size -= shift;

   363         if (buffer->pos >= shift) {

   364             buffer->pos -= shift;

   365         } else {

   366             buffer->pos = 0;

   367         }

   368     }

   369     return 0;

   370 }

   372 int cxBufferShiftRight(

   373         CxBuffer *buffer,

   374         size_t shift

   375 ) {

   376     size_t req_capacity = buffer->size + shift;

   377     size_t movebytes;

   379     // auto extend buffer, if required and enabled

   380     if (buffer->capacity < req_capacity) {

   381         if ((buffer->flags & CX_BUFFER_AUTO_EXTEND) == CX_BUFFER_AUTO_EXTEND) {

   382             if (cxBufferMinimumCapacity(buffer, req_capacity)) {

   383                 return 1;

   384             }

   385             movebytes = buffer->size;

   386         } else {

   387             movebytes = buffer->capacity - shift;

   388         }

   389     } else {

   390         movebytes = buffer->size;

   391     }

   393     memmove(buffer->bytes + shift, buffer->bytes, movebytes);

   394     buffer->size = shift + movebytes;

   396     buffer->pos += shift;

   397     if (buffer->pos > buffer->size) {

   398         buffer->pos = buffer->size;

   399     }

   401     return 0;

   402 }

   404 int cxBufferShift(

   405         CxBuffer *buffer,

   406         off_t shift

   407 ) {

   408     if (shift < 0) {

   409         return cxBufferShiftLeft(buffer, (size_t) (-shift));

   410     } else if (shift > 0) {

   411         return cxBufferShiftRight(buffer, (size_t) shift);

   412     } else {

   413         return 0;

   414     }

   415 }

Mercurial > hg > ucx / file revision

src/buffer.c@3390b58ad15a

src/buffer.c