Mon, 25 Jul 2022 15:34:19 +0200
#170 test cxBufferGet
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 <stdlib.h>
33 #include <stdio.h>
34 #include <string.h>
35 #include <stdint.h>
37 int cxBufferInit(
38 CxBuffer *buffer,
39 void *space,
40 size_t capacity,
41 CxAllocator const *allocator,
42 int flags
43 ) {
44 buffer->allocator = allocator;
45 buffer->flags = flags;
46 if (!space) {
47 buffer->bytes = cxMalloc(allocator, capacity);
48 if (buffer->bytes == NULL) {
49 return 1;
50 }
51 buffer->flags |= CX_BUFFER_FREE_CONTENTS;
52 } else {
53 buffer->bytes = space;
54 }
55 buffer->capacity = capacity;
56 buffer->size = 0;
57 buffer->pos = 0;
59 buffer->flush_func = NULL;
60 buffer->flush_target = NULL;
61 buffer->flush_blkmax = 0;
62 buffer->flush_blksize = 4096;
63 buffer->flush_threshold = SIZE_MAX;
65 return 0;
66 }
68 void cxBufferDestroy(CxBuffer *buffer) {
69 if ((buffer->flags & CX_BUFFER_FREE_CONTENTS) == CX_BUFFER_FREE_CONTENTS) {
70 cxFree(buffer->allocator, buffer->bytes);
71 }
72 }
74 int cxBufferSeek(
75 CxBuffer *buffer,
76 off_t offset,
77 int whence
78 ) {
79 size_t npos;
80 switch (whence) {
81 case SEEK_CUR:
82 npos = buffer->pos;
83 break;
84 case SEEK_END:
85 npos = buffer->size;
86 break;
87 case SEEK_SET:
88 npos = 0;
89 break;
90 default:
91 return -1;
92 }
94 size_t opos = npos;
95 npos += offset;
97 if ((offset > 0 && npos < opos) || (offset < 0 && npos > opos)) {
98 return -1;
99 }
101 if (npos >= buffer->size) {
102 return -1;
103 } else {
104 buffer->pos = npos;
105 return 0;
106 }
108 }
110 void cxBufferClear(CxBuffer *buffer) {
111 memset(buffer->bytes, 0, buffer->size);
112 buffer->size = 0;
113 buffer->pos = 0;
114 }
116 int cxBufferEof(CxBuffer const *buffer) {
117 return buffer->pos >= buffer->size;
118 }
120 int cxBufferMinimumCapacity(
121 CxBuffer *buffer,
122 size_t newcap
123 ) {
124 if (newcap <= buffer->capacity) {
125 return 0;
126 }
128 if (cxReallocate(buffer->allocator,
129 (void **) &buffer->bytes, newcap) == 0) {
130 buffer->capacity = newcap;
131 return 0;
132 } else {
133 return -1;
134 }
135 }
137 /**
138 * Helps flushing data to the flush target of a buffer.
139 *
140 * @param buffer the buffer containing the config
141 * @param space the data to flush
142 * @param size the element size
143 * @param nitems the number of items
144 * @return the number of items flushed
145 */
146 static size_t cx_buffer_write_flush_helper(
147 CxBuffer *buffer,
148 unsigned char const *space,
149 size_t size,
150 size_t nitems
151 ) {
152 size_t pos = 0;
153 size_t remaining = nitems;
154 size_t max_items = buffer->flush_blksize / size;
155 while (remaining > 0) {
156 size_t items = remaining > max_items ? max_items : remaining;
157 size_t flushed = buffer->flush_func(
158 space + pos,
159 size, items,
160 buffer->flush_target);
161 if (flushed > 0) {
162 pos += (flushed * size);
163 remaining -= flushed;
164 } else {
165 // if no bytes can be flushed out anymore, we give up
166 break;
167 }
168 }
169 return nitems - remaining;
170 }
172 size_t cxBufferWrite(
173 void const *ptr,
174 size_t size,
175 size_t nitems,
176 CxBuffer *buffer
177 ) {
178 // optimize for easy case
179 if (size == 1 && (buffer->capacity - buffer->pos) >= nitems) {
180 memcpy(buffer->bytes + buffer->pos, ptr, nitems);
181 buffer->pos += nitems;
182 if (buffer->pos > buffer->size) {
183 buffer->size = buffer->pos;
184 }
185 return nitems;
186 }
188 size_t len;
189 size_t nitems_out = nitems;
190 if (cx_szmul(size, nitems, &len)) {
191 return 0;
192 }
193 size_t required = buffer->pos + len;
194 if (buffer->pos > required) {
195 return 0;
196 }
198 bool perform_flush = false;
199 if (required > buffer->capacity) {
200 if ((buffer->flags & CX_BUFFER_AUTO_EXTEND) == CX_BUFFER_AUTO_EXTEND && required) {
201 if (buffer->flush_blkmax > 0 && required > buffer->flush_threshold) {
202 perform_flush = true;
203 } else {
204 if (cxBufferMinimumCapacity(buffer, required)) {
205 return 0;
206 }
207 }
208 } else {
209 if (buffer->flush_blkmax > 0) {
210 perform_flush = true;
211 } else {
212 // truncate data to be written, if we can neither extend nor flush
213 len = buffer->capacity - buffer->pos;
214 if (size > 1) {
215 len -= len % size;
216 }
217 nitems_out = len / size;
218 }
219 }
220 }
222 if (len == 0) {
223 return len;
224 }
226 if (perform_flush) {
227 size_t flush_max;
228 if (cx_szmul(buffer->flush_blkmax, buffer->flush_blksize, &flush_max)) {
229 return 0;
230 }
231 size_t flush_pos = buffer->flush_func == NULL || buffer->flush_target == NULL
232 ? buffer->pos
233 : cx_buffer_write_flush_helper(buffer, buffer->bytes, 1, buffer->pos);
234 if (flush_pos == buffer->pos) {
235 // entire buffer has been flushed, we can reset
236 buffer->size = buffer->pos = 0;
238 size_t items_flush; // how many items can also be directly flushed
239 size_t items_keep; // how many items have to be written to the buffer
241 items_flush = flush_max >= required ? nitems : (flush_max - flush_pos) / size;
242 if (items_flush > 0) {
243 items_flush = cx_buffer_write_flush_helper(buffer, ptr, size, items_flush / size);
244 // in case we could not flush everything, keep the rest
245 }
246 items_keep = nitems - items_flush;
247 if (items_keep > 0) {
248 // try again with the remaining stuff
249 unsigned char const *new_ptr = ptr;
250 new_ptr += items_flush * size;
251 // report the directly flushed items as written plus the remaining stuff
252 return items_flush + cxBufferWrite(new_ptr, size, items_keep, buffer);
253 } else {
254 // all items have been flushed - report them as written
255 return nitems;
256 }
257 } else if (flush_pos == 0) {
258 // nothing could be flushed at all, we immediately give up without writing any data
259 return 0;
260 } else {
261 // we were partially successful, we shift left and try again
262 cxBufferShiftLeft(buffer, flush_pos);
263 return cxBufferWrite(ptr, size, nitems, buffer);
264 }
265 } else {
266 memcpy(buffer->bytes + buffer->pos, ptr, len);
267 buffer->pos += len;
268 if (buffer->pos > buffer->size) {
269 buffer->size = buffer->pos;
270 }
271 return nitems_out;
272 }
274 }
276 int cxBufferPut(
277 CxBuffer *buffer,
278 int c
279 ) {
280 c &= 0xFF;
281 unsigned char const ch = c;
282 if (cxBufferWrite(&ch, 1, 1, buffer) == 1) {
283 return c;
284 } else {
285 return EOF;
286 }
287 }
289 size_t cxBufferPutString(
290 CxBuffer *buffer,
291 const char *str
292 ) {
293 return cxBufferWrite(str, 1, strlen(str), buffer);
294 }
296 size_t cxBufferRead(
297 void *ptr,
298 size_t size,
299 size_t nitems,
300 CxBuffer *buffer
301 ) {
302 size_t len;
303 if (cx_szmul(size, nitems, &len)) {
304 return 0;
305 }
306 if (buffer->pos + len > buffer->size) {
307 len = buffer->size - buffer->pos;
308 if (size > 1) len -= len % size;
309 }
311 if (len <= 0) {
312 return len;
313 }
315 memcpy(ptr, buffer->bytes + buffer->pos, len);
316 buffer->pos += len;
318 return len / size;
319 }
321 int cxBufferGet(CxBuffer *buffer) {
322 if (cxBufferEof(buffer)) {
323 return EOF;
324 } else {
325 int c = buffer->bytes[buffer->pos];
326 buffer->pos++;
327 return c;
328 }
329 }
331 int cxBufferShiftLeft(
332 CxBuffer *buffer,
333 size_t shift
334 ) {
335 if (shift >= buffer->size) {
336 buffer->pos = buffer->size = 0;
337 } else {
338 memmove(buffer->bytes, buffer->bytes + shift, buffer->size - shift);
339 buffer->size -= shift;
341 if (buffer->pos >= shift) {
342 buffer->pos -= shift;
343 } else {
344 buffer->pos = 0;
345 }
346 }
347 return 0;
348 }
350 int cxBufferShiftRight(
351 CxBuffer *buffer,
352 size_t shift
353 ) {
354 size_t req_capacity = buffer->size + shift;
355 size_t movebytes;
357 // auto extend buffer, if required and enabled
358 if (buffer->capacity < req_capacity) {
359 if ((buffer->flags & CX_BUFFER_AUTO_EXTEND) == CX_BUFFER_AUTO_EXTEND) {
360 if (cxBufferMinimumCapacity(buffer, req_capacity)) {
361 return 1;
362 }
363 movebytes = buffer->size;
364 } else {
365 movebytes = buffer->capacity - shift;
366 }
367 } else {
368 movebytes = buffer->size;
369 }
371 memmove(buffer->bytes + shift, buffer->bytes, movebytes);
372 buffer->size = shift + movebytes;
374 buffer->pos += shift;
375 if (buffer->pos > buffer->size) {
376 buffer->pos = buffer->size;
377 }
379 return 0;
380 }
382 int cxBufferShift(
383 CxBuffer *buffer,
384 off_t shift
385 ) {
386 if (shift < 0) {
387 return cxBufferShiftLeft(buffer, (size_t) (-shift));
388 } else if (shift > 0) {
389 return cxBufferShiftRight(buffer, (size_t) shift);
390 } else {
391 return 0;
392 }
393 }