/** @file
 * IPRT - Assembly Routines for Optimizing some Integers Math Operations.
 */

/*
 * Copyright (C) 2006-2016 Oracle Corporation
 *
 * This file is part of VirtualBox Open Source Edition (OSE), as
 * available from http://www.virtualbox.org. This file is free software;
 * you can redistribute it and/or modify it under the terms of the GNU
 * General Public License (GPL) as published by the Free Software
 * Foundation, in version 2 as it comes in the "COPYING" file of the
 * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
 * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
 *
 * The contents of this file may alternatively be used under the terms
 * of the Common Development and Distribution License Version 1.0
 * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
 * VirtualBox OSE distribution, in which case the provisions of the
 * CDDL are applicable instead of those of the GPL.
 *
 * You may elect to license modified versions of this file under the
 * terms and conditions of either the GPL or the CDDL or both.
 */

#ifndef ___iprt_asm_math_h
#define ___iprt_asm_math_h

#include <iprt/types.h>

#if defined(_MSC_VER) && RT_INLINE_ASM_USES_INTRIN
# pragma warning(push)
# pragma warning(disable:4668)	/* Several incorrect __cplusplus uses. */
# pragma warning(disable:4255)	/* Incorrect __slwpcb prototype. */
# include <intrin.h>
# pragma warning(pop)
  /* Emit the intrinsics at all optimization levels. */
# pragma intrinsic(__emul)
# pragma intrinsic(__emulu)
# ifdef RT_ARCH_AMD64
#  pragma intrinsic(_mul128)
#  pragma intrinsic(_umul128)
# endif
#endif

/** @defgroup grp_rt_asm_math   Interger Math Optimizations
 * @ingroup grp_rt_asm
 * @{ */

/**
 * Multiplies two unsigned 32-bit values returning an unsigned 64-bit result.
 *
 * @returns u32F1 * u32F2.
 */

#if RT_INLINE_ASM_EXTERNAL && !RT_INLINE_ASM_USES_INTRIN && defined(RT_ARCH_X86)
DECLASM(uint64_t) ASMMult2xU32RetU64(uint32_t u32F1, uint32_t u32F2);
#else
DECLINLINE(uint64_t) ASMMult2xU32RetU64(uint32_t u32F1, uint32_t u32F2)
{
# ifdef RT_ARCH_X86
	uint64_t u64;
#  if RT_INLINE_ASM_GNU_STYLE
	__asm__ __volatile__("mull %%edx":"=A"(u64)
			     :"a"(u32F2), "d"(u32F1));
#  elif RT_INLINE_ASM_USES_INTRIN
	u64 = __emulu(u32F1, u32F2);
#  else
	__asm {
		mov edx,[u32F1]
		mov eax,[u32F2]
	mul edx mov dword ptr[u64], eax mov dword ptr[u64 + 4], edx}
#  endif
	return u64;
# else /* generic: */
	return (uint64_t) u32F1 *u32F2;
# endif
}
#endif

/**
 * Multiplies two signed 32-bit values returning a signed 64-bit result.
 *
 * @returns u32F1 * u32F2.
 */
#if RT_INLINE_ASM_EXTERNAL && !RT_INLINE_ASM_USES_INTRIN && defined(RT_ARCH_X86)
DECLASM(int64_t) ASMMult2xS32RetS64(int32_t i32F1, int32_t i32F2);
#else
DECLINLINE(int64_t) ASMMult2xS32RetS64(int32_t i32F1, int32_t i32F2)
{
# ifdef RT_ARCH_X86
	int64_t i64;
#  if RT_INLINE_ASM_GNU_STYLE
	__asm__ __volatile__("imull %%edx":"=A"(i64)
			     :"a"(i32F2), "d"(i32F1));
#  elif RT_INLINE_ASM_USES_INTRIN
	i64 = __emul(i32F1, i32F2);
#  else
	__asm {
		mov edx,[i32F1]
		mov eax,[i32F2]
	imul edx mov dword ptr[i64], eax mov dword ptr[i64 + 4], edx}
#  endif
	return i64;
# else /* generic: */
	return (int64_t) i32F1 *i32F2;
# endif
}
#endif

#if ARCH_BITS == 64
DECLINLINE(uint64_t) ASMMult2xU64Ret2xU64(uint64_t u64F1, uint64_t u64F2,
					  uint64_t * pu64ProdHi)
{
# if defined(RT_ARCH_AMD64) && (RT_INLINE_ASM_GNU_STYLE || RT_INLINE_ASM_USES_INTRIN)
#  if RT_INLINE_ASM_GNU_STYLE
	uint64_t u64Low, u64High;
	__asm__ __volatile__("mulq %%rdx":"=a"(u64Low), "=d"(u64High)
			     :"0"(u64F1), "1"(u64F2));
	*pu64ProdHi = u64High;
	return u64Low;
#  elif RT_INLINE_ASM_USES_INTRIN
	return _umul128(u64F1, u64F2, pu64ProdHi);
#  else
#   error "hmm"
#  endif
# else /* generic: */
	/*
	 *   F1 * F2 = Prod
	 *   --   --
	 *   ab * cd =  b*d + a*d*10  +  b*c*10 + a*c*100
	 *
	 * Where a, b, c and d are 'digits', and 10 is max digit + 1.
	 *
	 * Our digits are 32-bit wide, so instead of 10 we multiply by 4G.
	 *  Prod = F1.s.Lo*F2.s.Lo    + F1.s.Hi*F2.s.Lo*4G
	 *       + F1.s.Lo*F2.s.Hi*4G + F1.s.Hi*F2.s.Hi*4G*4G
	 */
	RTUINT128U Prod;
	RTUINT64U Tmp1;
	uint64_t u64Tmp;
	RTUINT64U F1, F2;
	F1.u = u64F1;
	F2.u = u64F2;

	Prod.s.Lo = ASMMult2xU32RetU64(F1.s.Lo, F2.s.Lo);

	Tmp1.u = ASMMult2xU32RetU64(F1.s.Hi, F2.s.Lo);
	u64Tmp = (uint64_t) Prod.DWords.dw1 + Tmp1.s.Lo;
	Prod.DWords.dw1 = (uint32_t) u64Tmp;
	Prod.s.Hi = Tmp1.s.Hi;
	Prod.s.Hi += u64Tmp >> 32;	/* carry */

	Tmp1.u = ASMMult2xU32RetU64(F1.s.Lo, F2.s.Hi);
	u64Tmp = (uint64_t) Prod.DWords.dw1 + Tmp1.s.Lo;
	Prod.DWords.dw1 = (uint32_t) u64Tmp;
	u64Tmp >>= 32;		/* carry */
	u64Tmp += Prod.DWords.dw2;
	u64Tmp += Tmp1.s.Hi;
	Prod.DWords.dw2 = (uint32_t) u64Tmp;
	Prod.DWords.dw3 += u64Tmp >> 32;	/* carry */

	Prod.s.Hi += ASMMult2xU32RetU64(F1.s.Hi, F2.s.Hi);
	*pu64ProdHi = Prod.s.Hi;
	return Prod.s.Lo;
# endif
}
#endif

/**
 * Divides a 64-bit unsigned by a 32-bit unsigned returning an unsigned 32-bit result.
 *
 * @returns u64 / u32.
 */
#if RT_INLINE_ASM_EXTERNAL && defined(RT_ARCH_X86)
DECLASM(uint32_t) ASMDivU64ByU32RetU32(uint64_t u64, uint32_t u32);
#else
DECLINLINE(uint32_t) ASMDivU64ByU32RetU32(uint64_t u64, uint32_t u32)
{
# ifdef RT_ARCH_X86
#  if RT_INLINE_ASM_GNU_STYLE
	RTCCUINTREG uDummy;
	__asm__ __volatile__("divl %3":"=a"(u32), "=d"(uDummy)
			     :"A"(u64), "r"(u32));
#  else
	__asm {
		mov eax, dword ptr[u64]
		mov edx, dword ptr[u64 + 4]
		mov ecx,[u32]
	div ecx mov[u32], eax}
#  endif
	return u32;
# else /* generic: */
	return (uint32_t) (u64 / u32);
# endif
}
#endif

/**
 * Divides a 64-bit signed by a 32-bit signed returning a signed 32-bit result.
 *
 * @returns u64 / u32.
 */
#if RT_INLINE_ASM_EXTERNAL && defined(RT_ARCH_X86)
DECLASM(int32_t) ASMDivS64ByS32RetS32(int64_t i64, int32_t i32);
#else
DECLINLINE(int32_t) ASMDivS64ByS32RetS32(int64_t i64, int32_t i32)
{
# ifdef RT_ARCH_X86
#  if RT_INLINE_ASM_GNU_STYLE
	RTCCUINTREG iDummy;
	__asm__ __volatile__("idivl %3":"=a"(i32), "=d"(iDummy)
			     :"A"(i64), "r"(i32));
#  else
	__asm {
		mov eax, dword ptr[i64]
		mov edx, dword ptr[i64 + 4]
		mov ecx,[i32]
	idiv ecx mov[i32], eax}
#  endif
	return i32;
# else /* generic: */
	return (int32_t) (i64 / i32);
# endif
}
#endif

/**
 * Performs 64-bit unsigned by a 32-bit unsigned division with a 32-bit unsigned result,
 * returning the rest.
 *
 * @returns u64 % u32.
 *
 * @remarks It is important that the result is <= UINT32_MAX or we'll overflow and crash.
 */
#if RT_INLINE_ASM_EXTERNAL && defined(RT_ARCH_X86)
DECLASM(uint32_t) ASMModU64ByU32RetU32(uint64_t u64, uint32_t u32);
#else
DECLINLINE(uint32_t) ASMModU64ByU32RetU32(uint64_t u64, uint32_t u32)
{
# ifdef RT_ARCH_X86
#  if RT_INLINE_ASM_GNU_STYLE
	RTCCUINTREG uDummy;
	__asm__ __volatile__("divl %3":"=a"(uDummy), "=d"(u32)
			     :"A"(u64), "r"(u32));
#  else
	__asm {
		mov eax, dword ptr[u64]
		mov edx, dword ptr[u64 + 4]
		mov ecx,[u32]
	div ecx mov[u32], edx}
#  endif
	return u32;
# else /* generic: */
	return (uint32_t) (u64 % u32);
# endif
}
#endif

/**
 * Performs 64-bit signed by a 32-bit signed division with a 32-bit signed result,
 * returning the rest.
 *
 * @returns u64 % u32.
 *
 * @remarks It is important that the result is <= UINT32_MAX or we'll overflow and crash.
 */
#if RT_INLINE_ASM_EXTERNAL && defined(RT_ARCH_X86)
DECLASM(int32_t) ASMModS64ByS32RetS32(int64_t i64, int32_t i32);
#else
DECLINLINE(int32_t) ASMModS64ByS32RetS32(int64_t i64, int32_t i32)
{
# ifdef RT_ARCH_X86
#  if RT_INLINE_ASM_GNU_STYLE
	RTCCUINTREG iDummy;
	__asm__ __volatile__("idivl %3":"=a"(iDummy), "=d"(i32)
			     :"A"(i64), "r"(i32));
#  else
	__asm {
		mov eax, dword ptr[i64]
		mov edx, dword ptr[i64 + 4]
		mov ecx,[i32]
	idiv ecx mov[i32], edx}
#  endif
	return i32;
# else /* generic: */
	return (int32_t) (i64 % i32);
# endif
}
#endif

/**
 * Multiple a 32-bit by a 32-bit integer and divide the result by a 32-bit integer
 * using a 64 bit intermediate result.
 *
 * @returns (u32A * u32B) / u32C.
 * @param   u32A    The 32-bit value (A).
 * @param   u32B    The 32-bit value to multiple by A.
 * @param   u32C    The 32-bit value to divide A*B by.
 *
 * @remarks Architecture specific.
 * @remarks Make sure the result won't ever exceed 32-bit, because hardware
 *          exception may be raised if it does.
 * @remarks On x86 this may be used to avoid dragging in 64-bit builtin
 *          arithmetics functions.
 */
#if RT_INLINE_ASM_EXTERNAL && (defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86))
DECLASM(uint32_t) ASMMultU32ByU32DivByU32(uint32_t u32A, uint32_t u32B,
					  uint32_t u32C);
#else
DECLINLINE(uint32_t) ASMMultU32ByU32DivByU32(uint32_t u32A, uint32_t u32B,
					     uint32_t u32C)
{
# if RT_INLINE_ASM_GNU_STYLE && (defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86))
	uint32_t u32Result, u32Spill;
	__asm__ __volatile__("mull %2\n\t"
			     "divl %3\n\t":"=&a"(u32Result), "=&d"(u32Spill)
			     :"r"(u32B), "r"(u32C), "0"(u32A));
	return u32Result;
# else
	return (uint32_t) (((uint64_t) u32A * u32B) / u32C);
# endif
}
#endif

/**
 * Multiple a 64-bit by a 32-bit integer and divide the result by a 32-bit integer
 * using a 96 bit intermediate result.
 *
 * @returns (u64A * u32B) / u32C.
 * @param   u64A    The 64-bit value.
 * @param   u32B    The 32-bit value to multiple by A.
 * @param   u32C    The 32-bit value to divide A*B by.
 *
 * @remarks Architecture specific.
 * @remarks Make sure the result won't ever exceed 64-bit, because hardware
 *          exception may be raised if it does.
 * @remarks On x86 this may be used to avoid dragging in 64-bit builtin
 *          arithmetics function.
 */
#if RT_INLINE_ASM_EXTERNAL || !defined(__GNUC__) || (!defined(RT_ARCH_AMD64) && !defined(RT_ARCH_X86))
DECLASM(uint64_t) ASMMultU64ByU32DivByU32(uint64_t u64A, uint32_t u32B,
					  uint32_t u32C);
#else
DECLINLINE(uint64_t) ASMMultU64ByU32DivByU32(uint64_t u64A, uint32_t u32B,
					     uint32_t u32C)
{
# if RT_INLINE_ASM_GNU_STYLE
#  ifdef RT_ARCH_AMD64
	uint64_t u64Result, u64Spill;
	__asm__ __volatile__("mulq %2\n\t"
			     "divq %3\n\t":"=&a"(u64Result), "=&d"(u64Spill)
			     :"r"((uint64_t) u32B),
			     "r"((uint64_t) u32C), "0"(u64A));
	return u64Result;
#  else
	uint32_t u32Dummy;
	uint64_t u64Result;
	__asm__ __volatile__("mull %%ecx       \n\t"	/* eax = u64Lo.lo = (u64A.lo * u32B).lo
							   edx = u64Lo.hi = (u64A.lo * u32B).hi */
			     "xchg %%eax,%%esi \n\t"	/* esi = u64Lo.lo
							   eax = u64A.hi */
			     "xchg %%edx,%%edi \n\t"	/* edi = u64Low.hi
							   edx = u32C */
			     "xchg %%edx,%%ecx \n\t"	/* ecx = u32C
							   edx = u32B */
			     "mull %%edx       \n\t"	/* eax = u64Hi.lo = (u64A.hi * u32B).lo
							   edx = u64Hi.hi = (u64A.hi * u32B).hi */
			     "addl %%edi,%%eax \n\t"	/* u64Hi.lo += u64Lo.hi */
			     "adcl $0,%%edx    \n\t"	/* u64Hi.hi += carry */
			     "divl %%ecx       \n\t"	/* eax = u64Hi / u32C
							   edx = u64Hi % u32C */
			     "movl %%eax,%%edi \n\t"	/* edi = u64Result.hi = u64Hi / u32C */
			     "movl %%esi,%%eax \n\t"	/* eax = u64Lo.lo */
			     "divl %%ecx       \n\t"	/* u64Result.lo */
			     "movl %%edi,%%edx \n\t"	/* u64Result.hi */
			     :"=A"(u64Result), "=c"(u32Dummy),
			     "=S"(u32Dummy), "=D"(u32Dummy)
			     :"a"((uint32_t) u64A),
			     "S"((uint32_t) (u64A >> 32)),
			     "c"(u32B), "D"(u32C));
	return u64Result;
#  endif
# else
	RTUINT64U u;
	uint64_t u64Lo = (uint64_t) (u64A & 0xffffffff) * u32B;
	uint64_t u64Hi = (uint64_t) (u64A >> 32) * u32B;
	u64Hi += (u64Lo >> 32);
	u.s.Hi = (uint32_t) (u64Hi / u32C);
	u.s.Lo =
	    (uint32_t) ((((u64Hi % u32C) << 32) + (u64Lo & 0xffffffff)) / u32C);
	return u.u;
# endif
}
#endif

/** @} */
#endif
