/* ***** BEGIN LICENSE BLOCK ***** 
 * Version: RCSL 1.0/RPSL 1.0 
 *  
 * Portions Copyright (c) 1995-2002 RealNetworks, Inc. All Rights Reserved. 
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 * the file under the RealNetworks Community Source License Version 1.0 
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 * in which case the RCSL will apply. You may also obtain the license terms 
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 * applicable to this file, the RCSL.  Please see the applicable RPSL or 
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 *  
 * This file is part of the Helix DNA Technology. RealNetworks is the 
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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 <inttypes.h>
typedef int64_t Word64;

#if (defined _WIN32 && !defined _WIN32_WCE) || (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 */

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

static __inline int FASTABS(int x) 
{
	int sign;

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

	return x;
}

static __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

static __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)); */
}

static __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
		}
	}
}

static __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
int MULSHIFT32(int x, int y);

static __inline int FASTABS(int x) 
{
	int sign;

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

	return x;
}

static __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

static __inline int MULSHIFT32(int x, int 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;
}

static __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;
}

static __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;

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

static __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;

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

	return sum64;
}
	
#else

static __inline int MULSHIFT32(int x, int 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

static __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;
}

static __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;

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

static __inline int FASTABS(int x) 
{
	int sign;

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

	return x;
}

static __inline int CLZ(int x)
{
	int numZeros;

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

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

	return numZeros;
}

static __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;
}

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

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

#elif defined(ARDUINO) || defined(ESP32) || defined(__APPLE__) || defined(__unix__)

static __inline int FASTABS(int x)
{
  int sign;

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

  return x;
}

static __inline int CLZ(int x)
{
  int numZeros;

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

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

  return numZeros;
}

/* returns 64-bit value in [edx:eax] */
static __inline Word64 MADD64(Word64 sum64, int x, int y)
{
    sum64 += (Word64)x * (Word64)y;
    return sum64;
}

static __inline__ int MULSHIFT32(int x, int y)
{
    int z;

    z = (Word64)x * (Word64)y >> 32;

        return z;
}

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

#else

#error Unsupported platform in assembly.h

#endif

#endif	/* platforms */

#endif /* _ASSEMBLY_H */
