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source: vbox/trunk/include/iprt/asm-math.h@ 75155

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1/** @file
2 * IPRT - Assembly Routines for Optimizing some Integers Math Operations.
3 */
4
5/*
6 * Copyright (C) 2006-2017 Oracle Corporation
7 *
8 * This file is part of VirtualBox Open Source Edition (OSE), as
9 * available from http://www.virtualbox.org. This file is free software;
10 * you can redistribute it and/or modify it under the terms of the GNU
11 * General Public License (GPL) as published by the Free Software
12 * Foundation, in version 2 as it comes in the "COPYING" file of the
13 * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
14 * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
15 *
16 * The contents of this file may alternatively be used under the terms
17 * of the Common Development and Distribution License Version 1.0
18 * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
19 * VirtualBox OSE distribution, in which case the provisions of the
20 * CDDL are applicable instead of those of the GPL.
21 *
22 * You may elect to license modified versions of this file under the
23 * terms and conditions of either the GPL or the CDDL or both.
24 */
25
26#ifndef ___iprt_asm_math_h
27#define ___iprt_asm_math_h
28
29#include <iprt/types.h>
30
31#if defined(_MSC_VER) && RT_INLINE_ASM_USES_INTRIN
32# pragma warning(push)
33# pragma warning(disable:4668) /* Several incorrect __cplusplus uses. */
34# pragma warning(disable:4255) /* Incorrect __slwpcb prototype. */
35# include <intrin.h>
36# pragma warning(pop)
37 /* Emit the intrinsics at all optimization levels. */
38# pragma intrinsic(__emul)
39# pragma intrinsic(__emulu)
40# ifdef RT_ARCH_AMD64
41# pragma intrinsic(_mul128)
42# pragma intrinsic(_umul128)
43# endif
44#endif
45
46
47/** @defgroup grp_rt_asm_math Interger Math Optimizations
48 * @ingroup grp_rt_asm
49 * @{ */
50
51/**
52 * Multiplies two unsigned 32-bit values returning an unsigned 64-bit result.
53 *
54 * @returns u32F1 * u32F2.
55 */
56
57#if RT_INLINE_ASM_EXTERNAL && !RT_INLINE_ASM_USES_INTRIN && defined(RT_ARCH_X86)
58DECLASM(uint64_t) ASMMult2xU32RetU64(uint32_t u32F1, uint32_t u32F2);
59#else
60DECLINLINE(uint64_t) ASMMult2xU32RetU64(uint32_t u32F1, uint32_t u32F2)
61{
62# ifdef RT_ARCH_X86
63 uint64_t u64;
64# if RT_INLINE_ASM_GNU_STYLE
65 __asm__ __volatile__("mull %%edx"
66 : "=A" (u64)
67 : "a" (u32F2), "d" (u32F1));
68# elif RT_INLINE_ASM_USES_INTRIN
69 u64 = __emulu(u32F1, u32F2);
70# else
71 __asm
72 {
73 mov edx, [u32F1]
74 mov eax, [u32F2]
75 mul edx
76 mov dword ptr [u64], eax
77 mov dword ptr [u64 + 4], edx
78 }
79# endif
80 return u64;
81# else /* generic: */
82 return (uint64_t)u32F1 * u32F2;
83# endif
84}
85#endif
86
87
88/**
89 * Multiplies two signed 32-bit values returning a signed 64-bit result.
90 *
91 * @returns u32F1 * u32F2.
92 */
93#if RT_INLINE_ASM_EXTERNAL && !RT_INLINE_ASM_USES_INTRIN && defined(RT_ARCH_X86)
94DECLASM(int64_t) ASMMult2xS32RetS64(int32_t i32F1, int32_t i32F2);
95#else
96DECLINLINE(int64_t) ASMMult2xS32RetS64(int32_t i32F1, int32_t i32F2)
97{
98# ifdef RT_ARCH_X86
99 int64_t i64;
100# if RT_INLINE_ASM_GNU_STYLE
101 __asm__ __volatile__("imull %%edx"
102 : "=A" (i64)
103 : "a" (i32F2), "d" (i32F1));
104# elif RT_INLINE_ASM_USES_INTRIN
105 i64 = __emul(i32F1, i32F2);
106# else
107 __asm
108 {
109 mov edx, [i32F1]
110 mov eax, [i32F2]
111 imul edx
112 mov dword ptr [i64], eax
113 mov dword ptr [i64 + 4], edx
114 }
115# endif
116 return i64;
117# else /* generic: */
118 return (int64_t)i32F1 * i32F2;
119# endif
120}
121#endif
122
123
124#if ARCH_BITS == 64
125DECLINLINE(uint64_t) ASMMult2xU64Ret2xU64(uint64_t u64F1, uint64_t u64F2, uint64_t *pu64ProdHi)
126{
127# if defined(RT_ARCH_AMD64) && (RT_INLINE_ASM_GNU_STYLE || RT_INLINE_ASM_USES_INTRIN)
128# if RT_INLINE_ASM_GNU_STYLE
129 uint64_t u64Low, u64High;
130 __asm__ __volatile__("mulq %%rdx"
131 : "=a" (u64Low), "=d" (u64High)
132 : "0" (u64F1), "1" (u64F2));
133 *pu64ProdHi = u64High;
134 return u64Low;
135# elif RT_INLINE_ASM_USES_INTRIN
136 return _umul128(u64F1, u64F2, pu64ProdHi);
137# else
138# error "hmm"
139# endif
140# else /* generic: */
141 /*
142 * F1 * F2 = Prod
143 * -- --
144 * ab * cd = b*d + a*d*10 + b*c*10 + a*c*100
145 *
146 * Where a, b, c and d are 'digits', and 10 is max digit + 1.
147 *
148 * Our digits are 32-bit wide, so instead of 10 we multiply by 4G.
149 * Prod = F1.s.Lo*F2.s.Lo + F1.s.Hi*F2.s.Lo*4G
150 * + F1.s.Lo*F2.s.Hi*4G + F1.s.Hi*F2.s.Hi*4G*4G
151 */
152 RTUINT128U Prod;
153 RTUINT64U Tmp1;
154 uint64_t u64Tmp;
155 RTUINT64U F1, F2;
156 F1.u = u64F1;
157 F2.u = u64F2;
158
159 Prod.s.Lo = ASMMult2xU32RetU64(F1.s.Lo, F2.s.Lo);
160
161 Tmp1.u = ASMMult2xU32RetU64(F1.s.Hi, F2.s.Lo);
162 u64Tmp = (uint64_t)Prod.DWords.dw1 + Tmp1.s.Lo;
163 Prod.DWords.dw1 = (uint32_t)u64Tmp;
164 Prod.s.Hi = Tmp1.s.Hi;
165 Prod.s.Hi += u64Tmp >> 32; /* carry */
166
167 Tmp1.u = ASMMult2xU32RetU64(F1.s.Lo, F2.s.Hi);
168 u64Tmp = (uint64_t)Prod.DWords.dw1 + Tmp1.s.Lo;
169 Prod.DWords.dw1 = (uint32_t)u64Tmp;
170 u64Tmp >>= 32; /* carry */
171 u64Tmp += Prod.DWords.dw2;
172 u64Tmp += Tmp1.s.Hi;
173 Prod.DWords.dw2 = (uint32_t)u64Tmp;
174 Prod.DWords.dw3 += u64Tmp >> 32; /* carry */
175
176 Prod.s.Hi += ASMMult2xU32RetU64(F1.s.Hi, F2.s.Hi);
177 *pu64ProdHi = Prod.s.Hi;
178 return Prod.s.Lo;
179# endif
180}
181#endif
182
183
184
185/**
186 * Divides a 64-bit unsigned by a 32-bit unsigned returning an unsigned 32-bit result.
187 *
188 * @returns u64 / u32.
189 */
190#if RT_INLINE_ASM_EXTERNAL && defined(RT_ARCH_X86)
191DECLASM(uint32_t) ASMDivU64ByU32RetU32(uint64_t u64, uint32_t u32);
192#else
193DECLINLINE(uint32_t) ASMDivU64ByU32RetU32(uint64_t u64, uint32_t u32)
194{
195# ifdef RT_ARCH_X86
196# if RT_INLINE_ASM_GNU_STYLE
197 RTCCUINTREG uDummy;
198 __asm__ __volatile__("divl %3"
199 : "=a" (u32), "=d"(uDummy)
200 : "A" (u64), "r" (u32));
201# else
202 __asm
203 {
204 mov eax, dword ptr [u64]
205 mov edx, dword ptr [u64 + 4]
206 mov ecx, [u32]
207 div ecx
208 mov [u32], eax
209 }
210# endif
211 return u32;
212# else /* generic: */
213 return (uint32_t)(u64 / u32);
214# endif
215}
216#endif
217
218
219/**
220 * Divides a 64-bit signed by a 32-bit signed returning a signed 32-bit result.
221 *
222 * @returns u64 / u32.
223 */
224#if RT_INLINE_ASM_EXTERNAL && defined(RT_ARCH_X86)
225DECLASM(int32_t) ASMDivS64ByS32RetS32(int64_t i64, int32_t i32);
226#else
227DECLINLINE(int32_t) ASMDivS64ByS32RetS32(int64_t i64, int32_t i32)
228{
229# ifdef RT_ARCH_X86
230# if RT_INLINE_ASM_GNU_STYLE
231 RTCCUINTREG iDummy;
232 __asm__ __volatile__("idivl %3"
233 : "=a" (i32), "=d"(iDummy)
234 : "A" (i64), "r" (i32));
235# else
236 __asm
237 {
238 mov eax, dword ptr [i64]
239 mov edx, dword ptr [i64 + 4]
240 mov ecx, [i32]
241 idiv ecx
242 mov [i32], eax
243 }
244# endif
245 return i32;
246# else /* generic: */
247 return (int32_t)(i64 / i32);
248# endif
249}
250#endif
251
252
253/**
254 * Performs 64-bit unsigned by a 32-bit unsigned division with a 32-bit unsigned result,
255 * returning the rest.
256 *
257 * @returns u64 % u32.
258 *
259 * @remarks It is important that the result is <= UINT32_MAX or we'll overflow and crash.
260 */
261#if RT_INLINE_ASM_EXTERNAL && defined(RT_ARCH_X86)
262DECLASM(uint32_t) ASMModU64ByU32RetU32(uint64_t u64, uint32_t u32);
263#else
264DECLINLINE(uint32_t) ASMModU64ByU32RetU32(uint64_t u64, uint32_t u32)
265{
266# ifdef RT_ARCH_X86
267# if RT_INLINE_ASM_GNU_STYLE
268 RTCCUINTREG uDummy;
269 __asm__ __volatile__("divl %3"
270 : "=a" (uDummy), "=d"(u32)
271 : "A" (u64), "r" (u32));
272# else
273 __asm
274 {
275 mov eax, dword ptr [u64]
276 mov edx, dword ptr [u64 + 4]
277 mov ecx, [u32]
278 div ecx
279 mov [u32], edx
280 }
281# endif
282 return u32;
283# else /* generic: */
284 return (uint32_t)(u64 % u32);
285# endif
286}
287#endif
288
289
290/**
291 * Performs 64-bit signed by a 32-bit signed division with a 32-bit signed result,
292 * returning the rest.
293 *
294 * @returns u64 % u32.
295 *
296 * @remarks It is important that the result is <= UINT32_MAX or we'll overflow and crash.
297 */
298#if RT_INLINE_ASM_EXTERNAL && defined(RT_ARCH_X86)
299DECLASM(int32_t) ASMModS64ByS32RetS32(int64_t i64, int32_t i32);
300#else
301DECLINLINE(int32_t) ASMModS64ByS32RetS32(int64_t i64, int32_t i32)
302{
303# ifdef RT_ARCH_X86
304# if RT_INLINE_ASM_GNU_STYLE
305 RTCCUINTREG iDummy;
306 __asm__ __volatile__("idivl %3"
307 : "=a" (iDummy), "=d"(i32)
308 : "A" (i64), "r" (i32));
309# else
310 __asm
311 {
312 mov eax, dword ptr [i64]
313 mov edx, dword ptr [i64 + 4]
314 mov ecx, [i32]
315 idiv ecx
316 mov [i32], edx
317 }
318# endif
319 return i32;
320# else /* generic: */
321 return (int32_t)(i64 % i32);
322# endif
323}
324#endif
325
326
327/**
328 * Multiple a 32-bit by a 32-bit integer and divide the result by a 32-bit integer
329 * using a 64 bit intermediate result.
330 *
331 * @returns (u32A * u32B) / u32C.
332 * @param u32A The 32-bit value (A).
333 * @param u32B The 32-bit value to multiple by A.
334 * @param u32C The 32-bit value to divide A*B by.
335 *
336 * @remarks Architecture specific.
337 * @remarks Make sure the result won't ever exceed 32-bit, because hardware
338 * exception may be raised if it does.
339 * @remarks On x86 this may be used to avoid dragging in 64-bit builtin
340 * arithmetics functions.
341 */
342#if RT_INLINE_ASM_EXTERNAL && (defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86))
343DECLASM(uint32_t) ASMMultU32ByU32DivByU32(uint32_t u32A, uint32_t u32B, uint32_t u32C);
344#else
345DECLINLINE(uint32_t) ASMMultU32ByU32DivByU32(uint32_t u32A, uint32_t u32B, uint32_t u32C)
346{
347# if RT_INLINE_ASM_GNU_STYLE && (defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86))
348 uint32_t u32Result, u32Spill;
349 __asm__ __volatile__("mull %2\n\t"
350 "divl %3\n\t"
351 : "=&a" (u32Result),
352 "=&d" (u32Spill)
353 : "r" (u32B),
354 "r" (u32C),
355 "0" (u32A));
356 return u32Result;
357# else
358 return (uint32_t)(((uint64_t)u32A * u32B) / u32C);
359# endif
360}
361#endif
362
363
364/**
365 * Multiple a 64-bit by a 32-bit integer and divide the result by a 32-bit integer
366 * using a 96 bit intermediate result.
367 *
368 * @returns (u64A * u32B) / u32C.
369 * @param u64A The 64-bit value.
370 * @param u32B The 32-bit value to multiple by A.
371 * @param u32C The 32-bit value to divide A*B by.
372 *
373 * @remarks Architecture specific.
374 * @remarks Make sure the result won't ever exceed 64-bit, because hardware
375 * exception may be raised if it does.
376 * @remarks On x86 this may be used to avoid dragging in 64-bit builtin
377 * arithmetics function.
378 */
379#if RT_INLINE_ASM_EXTERNAL || !defined(__GNUC__) || (!defined(RT_ARCH_AMD64) && !defined(RT_ARCH_X86))
380DECLASM(uint64_t) ASMMultU64ByU32DivByU32(uint64_t u64A, uint32_t u32B, uint32_t u32C);
381#else
382DECLINLINE(uint64_t) ASMMultU64ByU32DivByU32(uint64_t u64A, uint32_t u32B, uint32_t u32C)
383{
384# if RT_INLINE_ASM_GNU_STYLE
385# ifdef RT_ARCH_AMD64
386 uint64_t u64Result, u64Spill;
387 __asm__ __volatile__("mulq %2\n\t"
388 "divq %3\n\t"
389 : "=&a" (u64Result),
390 "=&d" (u64Spill)
391 : "r" ((uint64_t)u32B),
392 "r" ((uint64_t)u32C),
393 "0" (u64A));
394 return u64Result;
395# else
396 uint32_t u32Dummy;
397 uint64_t u64Result;
398 __asm__ __volatile__("mull %%ecx \n\t" /* eax = u64Lo.lo = (u64A.lo * u32B).lo
399 edx = u64Lo.hi = (u64A.lo * u32B).hi */
400 "xchg %%eax,%%esi \n\t" /* esi = u64Lo.lo
401 eax = u64A.hi */
402 "xchg %%edx,%%edi \n\t" /* edi = u64Low.hi
403 edx = u32C */
404 "xchg %%edx,%%ecx \n\t" /* ecx = u32C
405 edx = u32B */
406 "mull %%edx \n\t" /* eax = u64Hi.lo = (u64A.hi * u32B).lo
407 edx = u64Hi.hi = (u64A.hi * u32B).hi */
408 "addl %%edi,%%eax \n\t" /* u64Hi.lo += u64Lo.hi */
409 "adcl $0,%%edx \n\t" /* u64Hi.hi += carry */
410 "divl %%ecx \n\t" /* eax = u64Hi / u32C
411 edx = u64Hi % u32C */
412 "movl %%eax,%%edi \n\t" /* edi = u64Result.hi = u64Hi / u32C */
413 "movl %%esi,%%eax \n\t" /* eax = u64Lo.lo */
414 "divl %%ecx \n\t" /* u64Result.lo */
415 "movl %%edi,%%edx \n\t" /* u64Result.hi */
416 : "=A"(u64Result), "=c"(u32Dummy),
417 "=S"(u32Dummy), "=D"(u32Dummy)
418 : "a"((uint32_t)u64A),
419 "S"((uint32_t)(u64A >> 32)),
420 "c"(u32B),
421 "D"(u32C));
422 return u64Result;
423# endif
424# else
425 RTUINT64U u;
426 uint64_t u64Lo = (uint64_t)(u64A & 0xffffffff) * u32B;
427 uint64_t u64Hi = (uint64_t)(u64A >> 32) * u32B;
428 u64Hi += (u64Lo >> 32);
429 u.s.Hi = (uint32_t)(u64Hi / u32C);
430 u.s.Lo = (uint32_t)((((u64Hi % u32C) << 32) + (u64Lo & 0xffffffff)) / u32C);
431 return u.u;
432# endif
433}
434#endif
435
436/** @} */
437#endif
438
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