rt-thread/bsp/stm32_radio/mp3/real/assembly.h

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/**************************************************************************************
 * 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

#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

typedef long long Word64;

#define MULSHIFT32	xmp3_MULSHIFT32
extern int MULSHIFT32(int x, int y);


#define FASTABS	xmp3_FASTABS
int FASTABS(int 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(__GNUC__) && defined(ARM)

typedef long long Word64;

#define MULSHIFT32	xmp3_MULSHIFT32
extern int MULSHIFT32(int x, int y);


#define FASTABS	xmp3_FASTABS
int FASTABS(int 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;
}

#else

#error Unsupported platform in assembly.h

#endif	/* platforms */

#endif /* _ASSEMBLY_H */