sg.cpp@ 99248

Last change on this file since 99248 was 98103, checked in by vboxsync, 2 years ago
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1	/* $Id: sg.cpp 98103 2023-01-17 14:15:46Z vboxsync $ */
2	/** @file
3	* IPRT - S/G buffer handling.
4	*/
5
6	/*
7	* Copyright (C) 2010-2023 Oracle and/or its affiliates.
8	*
9	* This file is part of VirtualBox base platform packages, as
10	* available from https://www.virtualbox.org.
11	*
12	* This program is free software; you can redistribute it and/or
13	* modify it under the terms of the GNU General Public License
14	* as published by the Free Software Foundation, in version 3 of the
15	* License.
16	*
17	* This program is distributed in the hope that it will be useful, but
18	* WITHOUT ANY WARRANTY; without even the implied warranty of
19	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20	* General Public License for more details.
21	*
22	* You should have received a copy of the GNU General Public License
23	* along with this program; if not, see <https://www.gnu.org/licenses>.
24	*
25	* The contents of this file may alternatively be used under the terms
26	* of the Common Development and Distribution License Version 1.0
27	* (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
28	* in the VirtualBox distribution, in which case the provisions of the
29	* CDDL are applicable instead of those of the GPL.
30	*
31	* You may elect to license modified versions of this file under the
32	* terms and conditions of either the GPL or the CDDL or both.
33	*
34	* SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
35	*/
36
37
38	/*********************************************************************************************************************************
39	* Header Files *
40	*********************************************************************************************************************************/
41	#include <iprt/sg.h>
42	#include <iprt/string.h>
43	#include <iprt/assert.h>
44	#include <iprt/asm.h>
45
46
47	static void rtSgBufGet(PRTSGBUF pSgBuf, size_t pcbData)
48	{
49	size_t cbData;
50	void *pvBuf;
51
52	/* Check that the S/G buffer has memory left. */
53	if (RT_UNLIKELY( pSgBuf->idxSeg == pSgBuf->cSegs
54	&& !pSgBuf->cbSegLeft))
55	{
56	*pcbData = 0;
57	return NULL;
58	}
59
60	#ifndef RDESKTOP
61	AssertMsg( pSgBuf->cbSegLeft <= 128 * _1M
62	&& (uintptr_t)pSgBuf->pvSegCur >= (uintptr_t)pSgBuf->paSegs[pSgBuf->idxSeg].pvSeg
63	&& (uintptr_t)pSgBuf->pvSegCur + pSgBuf->cbSegLeft <= (uintptr_t)pSgBuf->paSegs[pSgBuf->idxSeg].pvSeg + pSgBuf->paSegs[pSgBuf->idxSeg].cbSeg,
64	("pSgBuf->idxSeg=%d pSgBuf->cSegs=%d pSgBuf->pvSegCur=%p pSgBuf->cbSegLeft=%zd pSgBuf->paSegs[%d].pvSeg=%p pSgBuf->paSegs[%d].cbSeg=%zd\n",
65	pSgBuf->idxSeg, pSgBuf->cSegs, pSgBuf->pvSegCur, pSgBuf->cbSegLeft, pSgBuf->idxSeg, pSgBuf->paSegs[pSgBuf->idxSeg].pvSeg, pSgBuf->idxSeg,
66	pSgBuf->paSegs[pSgBuf->idxSeg].cbSeg));
67	#endif
68
69	cbData = RT_MIN(*pcbData, pSgBuf->cbSegLeft);
70	pvBuf = pSgBuf->pvSegCur;
71	pSgBuf->cbSegLeft -= cbData;
72
73	/* Advance to the next segment if required. */
74	if (!pSgBuf->cbSegLeft)
75	{
76	pSgBuf->idxSeg++;
77
78	if (pSgBuf->idxSeg < pSgBuf->cSegs)
79	{
80	pSgBuf->pvSegCur = pSgBuf->paSegs[pSgBuf->idxSeg].pvSeg;
81	pSgBuf->cbSegLeft = pSgBuf->paSegs[pSgBuf->idxSeg].cbSeg;
82	}
83
84	*pcbData = cbData;
85	}
86	else
87	pSgBuf->pvSegCur = (uint8_t *)pSgBuf->pvSegCur + cbData;
88
89	return pvBuf;
90	}
91
92
93	RTDECL(void) RTSgBufInit(PRTSGBUF pSgBuf, PCRTSGSEG paSegs, size_t cSegs)
94	{
95	AssertPtr(pSgBuf);
96	Assert( (cSegs > 0 && RT_VALID_PTR(paSegs))
97	\|\| (!cSegs && !paSegs));
98	Assert(cSegs < (~(unsigned)0 >> 1));
99
100	pSgBuf->paSegs = paSegs;
101	pSgBuf->cSegs = (unsigned)cSegs;
102	pSgBuf->idxSeg = 0;
103	if (cSegs && paSegs)
104	{
105	pSgBuf->pvSegCur = paSegs[0].pvSeg;
106	pSgBuf->cbSegLeft = paSegs[0].cbSeg;
107	}
108	else
109	{
110	pSgBuf->pvSegCur = NULL;
111	pSgBuf->cbSegLeft = 0;
112	}
113	}
114
115
116	RTDECL(void) RTSgBufReset(PRTSGBUF pSgBuf)
117	{
118	AssertPtrReturnVoid(pSgBuf);
119
120	pSgBuf->idxSeg = 0;
121	if (pSgBuf->cSegs)
122	{
123	pSgBuf->pvSegCur = pSgBuf->paSegs[0].pvSeg;
124	pSgBuf->cbSegLeft = pSgBuf->paSegs[0].cbSeg;
125	}
126	else
127	{
128	pSgBuf->pvSegCur = NULL;
129	pSgBuf->cbSegLeft = 0;
130	}
131	}
132
133
134	RTDECL(void) RTSgBufClone(PRTSGBUF pSgBufTo, PCRTSGBUF pSgBufFrom)
135	{
136	AssertPtr(pSgBufTo);
137	AssertPtr(pSgBufFrom);
138
139	pSgBufTo->paSegs = pSgBufFrom->paSegs;
140	pSgBufTo->cSegs = pSgBufFrom->cSegs;
141	pSgBufTo->idxSeg = pSgBufFrom->idxSeg;
142	pSgBufTo->pvSegCur = pSgBufFrom->pvSegCur;
143	pSgBufTo->cbSegLeft = pSgBufFrom->cbSegLeft;
144	}
145
146
147	RTDECL(void ) RTSgBufGetNextSegment(PRTSGBUF pSgBuf, size_t pcbSeg)
148	{
149	AssertPtrReturn(pSgBuf, NULL);
150	AssertPtrReturn(pcbSeg, NULL);
151
152	if (!*pcbSeg)
153	*pcbSeg = pSgBuf->cbSegLeft;
154
155	return rtSgBufGet(pSgBuf, pcbSeg);
156	}
157
158
159	RTDECL(size_t) RTSgBufCopy(PRTSGBUF pSgBufDst, PRTSGBUF pSgBufSrc, size_t cbCopy)
160	{
161	AssertPtrReturn(pSgBufDst, 0);
162	AssertPtrReturn(pSgBufSrc, 0);
163
164	size_t cbLeft = cbCopy;
165	while (cbLeft)
166	{
167	size_t cbThisCopy = RT_MIN(RT_MIN(pSgBufDst->cbSegLeft, cbLeft), pSgBufSrc->cbSegLeft);
168	if (!cbThisCopy)
169	break;
170
171	size_t cbTmp = cbThisCopy;
172	void *pvBufDst = rtSgBufGet(pSgBufDst, &cbTmp);
173	Assert(cbTmp == cbThisCopy);
174	void *pvBufSrc = rtSgBufGet(pSgBufSrc, &cbTmp);
175	Assert(cbTmp == cbThisCopy);
176
177	memcpy(pvBufDst, pvBufSrc, cbThisCopy);
178
179	cbLeft -= cbThisCopy;
180	}
181
182	return cbCopy - cbLeft;
183	}
184
185
186	RTDECL(int) RTSgBufCmp(PCRTSGBUF pSgBuf1, PCRTSGBUF pSgBuf2, size_t cbCmp)
187	{
188	AssertPtrReturn(pSgBuf1, 0);
189	AssertPtrReturn(pSgBuf2, 0);
190
191	/* Set up the temporary buffers */
192	RTSGBUF SgBuf1;
193	RTSgBufClone(&SgBuf1, pSgBuf1);
194	RTSGBUF SgBuf2;
195	RTSgBufClone(&SgBuf2, pSgBuf2);
196
197	size_t cbLeft = cbCmp;
198	while (cbLeft)
199	{
200	size_t cbThisCmp = RT_MIN(RT_MIN(SgBuf1.cbSegLeft, cbLeft), SgBuf2.cbSegLeft);
201	if (!cbThisCmp)
202	break;
203
204	size_t cbTmp = cbThisCmp;
205	void *pvBuf1 = rtSgBufGet(&SgBuf1, &cbTmp);
206	Assert(cbTmp == cbThisCmp);
207	void *pvBuf2 = rtSgBufGet(&SgBuf2, &cbTmp);
208	Assert(cbTmp == cbThisCmp);
209
210	int rc = memcmp(pvBuf1, pvBuf2, cbThisCmp);
211	if (rc)
212	return rc;
213
214	cbLeft -= cbThisCmp;
215	}
216
217	return 0;
218	}
219
220
221	RTDECL(int) RTSgBufCmpEx(PRTSGBUF pSgBuf1, PRTSGBUF pSgBuf2, size_t cbCmp, size_t *poffDiff, bool fAdvance)
222	{
223	AssertPtrReturn(pSgBuf1, 0);
224	AssertPtrReturn(pSgBuf2, 0);
225
226	RTSGBUF SgBuf1Tmp;
227	RTSGBUF SgBuf2Tmp;
228	PRTSGBUF pSgBuf1Tmp;
229	PRTSGBUF pSgBuf2Tmp;
230
231	if (!fAdvance)
232	{
233	/* Set up the temporary buffers */
234	RTSgBufClone(&SgBuf1Tmp, pSgBuf1);
235	RTSgBufClone(&SgBuf2Tmp, pSgBuf2);
236	pSgBuf1Tmp = &SgBuf1Tmp;
237	pSgBuf2Tmp = &SgBuf2Tmp;
238	}
239	else
240	{
241	pSgBuf1Tmp = pSgBuf1;
242	pSgBuf2Tmp = pSgBuf2;
243	}
244
245	size_t cbLeft = cbCmp;
246	size_t off = 0;
247	while (cbLeft)
248	{
249	size_t cbThisCmp = RT_MIN(RT_MIN(pSgBuf1Tmp->cbSegLeft, cbLeft), pSgBuf2Tmp->cbSegLeft);
250	if (!cbThisCmp)
251	break;
252
253	size_t cbTmp = cbThisCmp;
254	uint8_t pbBuf1 = (uint8_t )rtSgBufGet(pSgBuf1Tmp, &cbTmp);
255	Assert(cbTmp == cbThisCmp);
256	uint8_t pbBuf2 = (uint8_t )rtSgBufGet(pSgBuf2Tmp, &cbTmp);
257	Assert(cbTmp == cbThisCmp);
258
259	int iDiff = memcmp(pbBuf1, pbBuf2, cbThisCmp);
260	if (iDiff)
261	{
262	/* Locate the first byte that differs if the caller requested this. */
263	if (poffDiff)
264	{
265	while ( cbThisCmp-- > 0
266	&& pbBuf1 == pbBuf2)
267	{
268	pbBuf1++;
269	pbBuf2++;
270	off++;
271	}
272
273	*poffDiff = off;
274	}
275	return iDiff;
276	}
277
278	cbLeft -= cbThisCmp;
279	off += cbThisCmp;
280	}
281
282	return 0;
283	}
284
285
286	RTDECL(size_t) RTSgBufSet(PRTSGBUF pSgBuf, uint8_t ubFill, size_t cbSet)
287	{
288	AssertPtrReturn(pSgBuf, 0);
289
290	size_t cbLeft = cbSet;
291
292	while (cbLeft)
293	{
294	size_t cbThisSet = cbLeft;
295	void *pvBuf = rtSgBufGet(pSgBuf, &cbThisSet);
296
297	if (!cbThisSet)
298	break;
299
300	memset(pvBuf, ubFill, cbThisSet);
301
302	cbLeft -= cbThisSet;
303	}
304
305	return cbSet - cbLeft;
306	}
307
308
309	RTDECL(size_t) RTSgBufCopyToBuf(PRTSGBUF pSgBuf, void *pvBuf, size_t cbCopy)
310	{
311	AssertPtrReturn(pSgBuf, 0);
312	AssertPtrReturn(pvBuf, 0);
313
314	size_t cbLeft = cbCopy;
315
316	while (cbLeft)
317	{
318	size_t cbThisCopy = cbLeft;
319	void *pvSrc = rtSgBufGet(pSgBuf, &cbThisCopy);
320
321	if (!cbThisCopy)
322	break;
323
324	memcpy(pvBuf, pvSrc, cbThisCopy);
325
326	cbLeft -= cbThisCopy;
327	pvBuf = (void *)((uintptr_t)pvBuf + cbThisCopy);
328	}
329
330	return cbCopy - cbLeft;
331	}
332
333
334	RTDECL(size_t) RTSgBufCopyFromBuf(PRTSGBUF pSgBuf, const void *pvBuf, size_t cbCopy)
335	{
336	AssertPtrReturn(pSgBuf, 0);
337	AssertPtrReturn(pvBuf, 0);
338
339	size_t cbLeft = cbCopy;
340
341	while (cbLeft)
342	{
343	size_t cbThisCopy = cbLeft;
344	void *pvDst = rtSgBufGet(pSgBuf, &cbThisCopy);
345
346	if (!cbThisCopy)
347	break;
348
349	memcpy(pvDst, pvBuf, cbThisCopy);
350
351	cbLeft -= cbThisCopy;
352	pvBuf = (const void *)((uintptr_t)pvBuf + cbThisCopy);
353	}
354
355	return cbCopy - cbLeft;
356	}
357
358
359	RTDECL(size_t) RTSgBufCopyToFn(PRTSGBUF pSgBuf, size_t cbCopy, PFNRTSGBUFCOPYTO pfnCopyTo, void *pvUser)
360	{
361	AssertPtrReturn(pSgBuf, 0);
362	AssertPtrReturn(pfnCopyTo, 0);
363
364	size_t cbLeft = cbCopy;
365
366	while (cbLeft)
367	{
368	size_t cbThisCopy = cbLeft;
369	void *pvSrc = rtSgBufGet(pSgBuf, &cbThisCopy);
370
371	if (!cbThisCopy)
372	break;
373
374	size_t cbThisCopied = pfnCopyTo(pSgBuf, pvSrc, cbThisCopy, pvUser);
375	cbLeft -= cbThisCopied;
376	if (cbThisCopied < cbThisCopy)
377	break;
378	}
379
380	return cbCopy - cbLeft;
381	}
382
383
384	RTDECL(size_t) RTSgBufCopyFromFn(PRTSGBUF pSgBuf, size_t cbCopy, PFNRTSGBUFCOPYFROM pfnCopyFrom, void *pvUser)
385	{
386	AssertPtrReturn(pSgBuf, 0);
387	AssertPtrReturn(pfnCopyFrom, 0);
388
389	size_t cbLeft = cbCopy;
390
391	while (cbLeft)
392	{
393	size_t cbThisCopy = cbLeft;
394	void *pvDst = rtSgBufGet(pSgBuf, &cbThisCopy);
395
396	if (!cbThisCopy)
397	break;
398
399	size_t cbThisCopied = pfnCopyFrom(pSgBuf, pvDst, cbThisCopy, pvUser);
400	cbLeft -= cbThisCopied;
401	if (cbThisCopied < cbThisCopy)
402	break;
403	}
404
405	return cbCopy - cbLeft;
406	}
407
408
409	RTDECL(size_t) RTSgBufAdvance(PRTSGBUF pSgBuf, size_t cbAdvance)
410	{
411	AssertPtrReturn(pSgBuf, 0);
412
413	size_t cbLeft = cbAdvance;
414	while (cbLeft)
415	{
416	size_t cbThisAdvance = cbLeft;
417	rtSgBufGet(pSgBuf, &cbThisAdvance);
418	if (!cbThisAdvance)
419	break;
420
421	cbLeft -= cbThisAdvance;
422	}
423
424	return cbAdvance - cbLeft;
425	}
426
427
428	RTDECL(size_t) RTSgBufSegArrayCreate(PRTSGBUF pSgBuf, PRTSGSEG paSeg, unsigned *pcSeg, size_t cbData)
429	{
430	AssertPtrReturn(pSgBuf, 0);
431	AssertPtrReturn(pcSeg, 0);
432
433	unsigned cSeg = 0;
434	size_t cb = 0;
435
436	if (!paSeg)
437	{
438	if (pSgBuf->cbSegLeft > 0)
439	{
440	size_t idx = pSgBuf->idxSeg;
441	cSeg = 1;
442
443	cb += RT_MIN(pSgBuf->cbSegLeft, cbData);
444	cbData -= RT_MIN(pSgBuf->cbSegLeft, cbData);
445
446	while ( cbData
447	&& idx < pSgBuf->cSegs - 1)
448	{
449	idx++;
450	cSeg++;
451	cb += RT_MIN(pSgBuf->paSegs[idx].cbSeg, cbData);
452	cbData -= RT_MIN(pSgBuf->paSegs[idx].cbSeg, cbData);
453	}
454	}
455	}
456	else
457	{
458	while ( cbData
459	&& cSeg < *pcSeg)
460	{
461	size_t cbThisSeg = cbData;
462	void *pvSeg = rtSgBufGet(pSgBuf, &cbThisSeg);
463
464	if (!cbThisSeg)
465	{
466	Assert(!pvSeg);
467	break;
468	}
469
470	AssertMsg(cbThisSeg <= cbData, ("Impossible!\n"));
471
472	paSeg[cSeg].cbSeg = cbThisSeg;
473	paSeg[cSeg].pvSeg = pvSeg;
474	cSeg++;
475	cbData -= cbThisSeg;
476	cb += cbThisSeg;
477	}
478	}
479
480	*pcSeg = cSeg;
481
482	return cb;
483	}
484
485
486	RTDECL(bool) RTSgBufIsZero(PRTSGBUF pSgBuf, size_t cbCheck)
487	{
488	RTSGBUF SgBufTmp;
489	RTSgBufClone(&SgBufTmp, pSgBuf);
490
491	bool fIsZero = true;
492	size_t cbLeft = cbCheck;
493	while (cbLeft)
494	{
495	size_t cbThisCheck = cbLeft;
496	void *pvBuf = rtSgBufGet(&SgBufTmp, &cbThisCheck);
497	if (!cbThisCheck)
498	break;
499	fIsZero = ASMMemIsZero(pvBuf, cbThisCheck);
500	if (!fIsZero)
501	break;
502	cbLeft -= cbThisCheck;
503	}
504
505	return fIsZero;
506	}
507

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source: vbox/trunk/src/VBox/Runtime/common/misc/sg.cpp@ 99248

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