/* ***** BEGIN LICENSE BLOCK ***** 
 * Version: RCSL 1.0/RPSL 1.0 
 *  
 * Portions Copyright (c) 1995-2002 RealNetworks, Inc. All Rights Reserved. 
 *      
 * The contents of this file, and the files included with this file, are 
 * subject to the current version of the RealNetworks Public Source License 
 * Version 1.0 (the "RPSL") available at 
 * http://www.helixcommunity.org/content/rpsl unless you have licensed 
 * the file under the RealNetworks Community Source License Version 1.0 
 * (the "RCSL") available at http://www.helixcommunity.org/content/rcsl, 
 * in which case the RCSL will apply. You may also obtain the license terms 
 * directly from RealNetworks.  You may not use this file except in 
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 * applicable to this file, the RCSL.  Please see the applicable RPSL or 
 * RCSL for the rights, obligations and limitations governing use of the 
 * contents of the file.  
 *  
 * This file is part of the Helix DNA Technology. RealNetworks is the 
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 * it created. 
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 *  
 * ***** END LICENSE BLOCK ***** */ 

/**************************************************************************************
 * Fixed-point MP3 decoder
 * Jon Recker (jrecker@real.com), Ken Cooke (kenc@real.com)
 * June 2003
 *
 * assembly.h - assembly language functions and prototypes for supported platforms
 *
 * - inline rountines with access to 64-bit multiply results 
 * - x86 (_WIN32) and ARM (ARM_ADS, _WIN32_WCE) versions included
 * - some inline functions are mix of asm and C for speed
 * - some functions are in native asm files, so only the prototype is given here
 *
 * MULSHIFT32(x, y)    signed multiply of two 32-bit integers (x and y), returns top 32 bits of 64-bit result
 * FASTABS(x)          branchless absolute value of signed integer x
 * CLZ(x)              count leading zeros in x
 * MADD64(sum, x, y)   (Windows only) sum [64-bit] += x [32-bit] * y [32-bit]
 * SHL64(sum, x, y)    (Windows only) 64-bit left shift using __int64
 * SAR64(sum, x, y)    (Windows only) 64-bit right shift using __int64
 */

#ifndef _ASSEMBLY_H
#define _ASSEMBLY_H

#include "fl/stl/noexcept.h"

namespace fl {
namespace third_party {

#if (defined _WIN32 && !defined _WIN32_WCE && defined _M_IX86) || (defined __WINS__ && defined _SYMBIAN) || defined(_OPENWAVE_SIMULATOR) || defined(WINCE_EMULATOR)    /* Symbian emulator for Ix86 */

#pragma warning( disable : 4035 )	/* complains about inline asm not returning a value */

__inline int32_t MULSHIFT32(int32_t x, int32_t y)
{
	__asm {
		mov		eax, x
		imul	y
		mov		eax, edx
	}
}

__inline int FASTABS(int x)
{
	int sign;

	sign = x >> (sizeof(int) * 8 - 1);
	x ^= sign;
	x -= sign;

	return x;
}

__inline int CLZ(int x)
{
	int numZeros;

	if (!x)
		return (sizeof(int) * 8);

	numZeros = 0;
	while (!(x & 0x80000000)) {
		numZeros++;
		x <<= 1;
	}

	return numZeros;
}

/* MADD64, SHL64, SAR64:
 * write in assembly to avoid dependency on run-time lib for 64-bit shifts, muls
 *  (sometimes compiler thunks to function calls instead of code generating)
 * required for Symbian emulator
 */
#ifdef __CW32__
typedef long long Word64;
#else
typedef __int64 Word64;
#endif

__inline Word64 MADD64(Word64 sum, int x, int y)
{
	unsigned int sumLo = ((unsigned int *)&sum)[0];
	int sumHi = ((int *)&sum)[1];

	__asm {
		mov		eax, x
		imul	y
		add		eax, sumLo
		adc		edx, sumHi
	}

	/* equivalent to return (sum + ((__int64)x * y)); */
}

__inline Word64 SHL64(Word64 x, int n)
{
	unsigned int xLo = ((unsigned int *)&x)[0];
	int xHi = ((int *)&x)[1];
	unsigned char nb = (unsigned char)n;

	if (n < 32) {
		__asm {
			mov		edx, xHi
			mov		eax, xLo
			mov		cl, nb
			shld    edx, eax, cl
			shl     eax, cl
		}
	} else if (n < 64) {
		/* shl masks cl to 0x1f */
		__asm {
			mov		edx, xLo
			mov		cl, nb
			xor     eax, eax
			shl     edx, cl
		}
	} else {
		__asm {
			xor		edx, edx
			xor		eax, eax
		}
	}
}

__inline Word64 SAR64(Word64 x, int n)
{
	unsigned int xLo = ((unsigned int *)&x)[0];
	int xHi = ((int *)&x)[1];
	unsigned char nb = (unsigned char)n;

	if (n < 32) {
		__asm {
			mov		edx, xHi
			mov		eax, xLo
			mov		cl, nb
			shrd	eax, edx, cl
			sar		edx, cl
		}
	} else if (n < 64) {
		/* sar masks cl to 0x1f */
		__asm {
			mov		edx, xHi
			mov		eax, xHi
			mov		cl, nb
			sar		edx, 31
			sar		eax, cl
		}
	} else {
		__asm {
			sar		xHi, 31
			mov		eax, xHi
			mov		edx, xHi
		}
	}
}

#elif (defined _WIN32) && (defined _WIN32_WCE)

/* use asm function for now (EVC++ 3.0 does horrible job compiling __int64 version) */
#define MULSHIFT32	xmp3_MULSHIFT32
int32_t MULSHIFT32(int32_t x, int32_t y);

__inline int FASTABS(int x)
{
	int sign;

	sign = x >> (sizeof(int) * 8 - 1);
	x ^= sign;
	x -= sign;

	return x;
}

__inline int CLZ(int x)
{
	int numZeros;

	if (!x)
		return (sizeof(int) * 8);

	numZeros = 0;
	while (!(x & 0x80000000)) {
		numZeros++;
		x <<= 1;
	}

	return numZeros;
}

#elif defined ARM_ADS

__inline int32_t MULSHIFT32(int32_t x, int32_t y)
{
	/* important rules for smull RdLo, RdHi, Rm, Rs:
	 *     RdHi and Rm can't be the same register
	 *     RdLo and Rm can't be the same register
	 *     RdHi and RdLo can't be the same register
	 * Note: Rs determines early termination (leading sign bits) so if you want to specify
	 *   which operand is Rs, put it in the SECOND argument (y)
	 * For inline assembly, x and y are not assumed to be R0, R1 so it shouldn't matter
	 *   which one is returned. (If this were a function call, returning y (R1) would 
	 *   require an extra "mov r0, r1")
	 */
	int zlow;
	__asm {
		smull zlow,y,x,y
	}

	return y;
}

__inline int FASTABS(int x)
{
	int t=0; /*Really is not necessary to initialiaze only to avoid warning*/

	__asm {
		eor	t, x, x, asr #31
		sub	t, t, x, asr #31
	}

	return t;
}

__inline int CLZ(int x)
{
	int numZeros;

	if (!x)
		return (sizeof(int) * 8);

	numZeros = 0;
	while (!(x & 0x80000000)) {
		numZeros++;
		x <<= 1;
	}

	return numZeros;
}

#elif defined(__GNUC__) && defined(ARM)

#if defined(ARM7DI)
	
typedef long long Word64;

__inline int32_t MULSHIFT32(int32_t x, int32_t y) {
	return x * y;
}

__inline Word64 SAR64(Word64 x, int n) {
	return x >>= n;
}


typedef union _U64 {
	Word64 w64;
	struct {
		/* x86 = little endian */
		unsigned int lo32;
		signed int   hi32;
	} r;
} U64;

__inline Word64 MADD64(Word64 sum64, int x, int y)
{
	sum64 += (Word64)x * (Word64)y;

	return sum64;
}

#else

__inline int32_t MULSHIFT32(int32_t x, int32_t y)
{
	/* important rules for smull RdLo, RdHi, Rm, Rs:
	 *     RdHi and Rm can't be the same register
	 *     RdLo and Rm can't be the same register
	 *     RdHi and RdLo can't be the same register
	 * Note: Rs determines early termination (leading sign bits) so if you want to specify
	 *   which operand is Rs, put it in the SECOND argument (y)
	 * For inline assembly, x and y are not assumed to be R0, R1 so it shouldn't matter
	 *   which one is returned. (If this were a function call, returning y (R1) would 
	 *   require an extra "mov r0, r1")
	 */
	int zlow;
	__asm__ volatile ("smull %0,%1,%2,%3" : "=&r" (zlow), "=r" (y) : "r" (x), "1" (y)) ;

	return y;
}

#endif

__inline int FASTABS(int x)
{
	int t=0; /*Really is not necessary to initialiaze only to avoid warning*/

	__asm__ volatile (
		"eor %0,%2,%2, asr #31;"
		"sub %0,%1,%2, asr #31;"
		: "=&r" (t)
		: "0" (t), "r" (x)
	 );

	return t;
}

__inline int CLZ(int x)
{
	int numZeros;

	if (!x)
		return (sizeof(int) * 8);

	numZeros = 0;
	while (!(x & 0x80000000)) {
		numZeros++;
		x <<= 1;
	}

	return numZeros;
}

#else

#ifdef __riscv

typedef long long Word64;

__inline int32_t MULSHIFT32(int32_t x, int32_t y)
{
	unsigned int result = 0;
	asm volatile ("mulh %0, %1, %2" : "=r"(result): "r"(x), "r"(y));
	return result;
}

__inline int FASTABS(int x) 
{
	int sign;

	sign = x >> (sizeof(int) * 8 - 1);
	x ^= sign;
	x -= sign;

	return x;
}

__inline int CLZ(int x)
{
	int numZeros;

	if (!x)
		return (sizeof(int) * 8);

	numZeros = 0;
	while (!(x & 0x80000000)) {
		numZeros++;
		x <<= 1;
	} 

	return numZeros;
}

__inline Word64 MADD64(Word64 sum, int a, int b)
{
	unsigned int result_hi = 0;
	unsigned int result_lo = 0;
	asm volatile ("mulh %0, %1, %2" : "=r"(result_hi): "r"(a), "r"(b));
	asm volatile ("mul  %0, %1, %2" : "=r"(result_lo): "r"(a), "r"(b));

	Word64 result = result_hi;
	result <<= 32;
	result += result_lo;
	result += sum;
	return result;
}

__inline Word64 SHL64(Word64 x, int n)
{
	return (x<<n);
}

__inline Word64 SAR64(Word64 x, int n)
{
	return (x >> n);
}

#elif defined(__xtensa__)

#include "xtensa/config/core-isa.h"

typedef long long Word64;

__inline Word64 MADD64(Word64 sum64, int x, int y)
{
    return (sum64 + ((long long)x * y));
}

#if XCHAL_HAVE_MUL32_HIGH

__inline int32_t MULSHIFT32(int32_t x, int32_t y)
{
    /* important rules for smull RdLo, RdHi, Rm, Rs:
     *     RdHi and Rm can't be the same register
     *     RdLo and Rm can't be the same register
     *     RdHi and RdLo can't be the same register
     * Note: Rs determines early termination (leading sign bits) so if you want to specify
     *   which operand is Rs, put it in the SECOND argument (y)
     * For inline assembly, x and y are not assumed to be R0, R1 so it doesn't matter
     *   which one is returned. (If this were a function call, returning y (R1) would
     *   require an extra "mov r0, r1")
     */
    int ret;
    asm volatile ("mulsh %0, %1, %2" : "=r" (ret) : "r" (x), "r" (y));
    return ret;
}

#else

// Fallback for Xtensa without MUL32_HIGH (e.g., ESP8266)
__inline int32_t MULSHIFT32(int32_t x, int32_t y) FL_NOEXCEPT
{
    Word64 result = ((Word64) x) * y;
    return (int32_t)(result >> 32);
}

#endif

#if XCHAL_HAVE_ABS

__inline int FASTABS(int x)
{
    int ret;
    asm volatile ("abs %0, %1" : "=r" (ret) : "r" (x));
    return ret;
}

#else

// Fallback for Xtensa without ABS instruction (e.g., ESP8266)
__inline int FASTABS(int x)
{
    int sign;
    sign = x >> (sizeof(int) * 8 - 1);
    x ^= sign;
    x -= sign;
    return x;
}

#endif

__inline Word64 SAR64(Word64 x, int n) FL_NOEXCEPT
{
    return x >> n;
}

__inline int CLZ(int x)
{
    return __builtin_clz(x);
}

#else

typedef long long Word64;

/**
 * Multiply together two 32-bit numbers and return the top 32-bits of the result.
 */
__inline int32_t MULSHIFT32(int32_t x, int32_t y) FL_NOEXCEPT
{
    Word64 result = ((Word64) x) * y;

    return (int32_t)(result >> 32);
}

/**
 * Absolute value of x
 */
__inline int32_t FASTABS(int32_t x) FL_NOEXCEPT
{
    int32_t sign;

    sign = x >> (sizeof(int32_t) * 8 - 1);
    x ^= sign;
    x -= sign;

    return x;
}

/**
 * Leading zeros
 */
__inline int32_t CLZ(int32_t x) FL_NOEXCEPT
{
    int32_t numZeros;

    if (!x)
        return (sizeof(int32_t) * 8);

    numZeros = 0;
    while (!(x & 0x80000000)) {
        numZeros++;
        x <<= 1;
    }

    return numZeros;
}

/**
 * Increase sum by x * y
 */
__inline Word64 MADD64(Word64 sum64, int x, int y) FL_NOEXCEPT
{
    sum64 += (Word64)x * (Word64)y;

    return sum64;
}

/**
 * Shift left
 */
__inline Word64 SHL64(Word64 x, int n) FL_NOEXCEPT
{
    return ((Word64) x) << n;
}

/**
 * Shift right
 */
__inline Word64 SAR64(Word64 x, int n) FL_NOEXCEPT
{
    return x >> n;
}

#endif

#endif	/* platforms */

} /* namespace third_party */
} /* namespace fl */

#endif /* _ASSEMBLY_H */
