text: /*
  	sample.h: The conversion from internal data to output samples of differing formats.
  
  	copyright 2007-9 by the mpg123 project - free software under the terms of the LGPL 2.1
  	see COPYING and AUTHORS files in distribution or http://mpg123.org
  	initially written by Thomas Orgis, taking WRITE_SAMPLE from decode.c
  	Later added the end-conversion specific macros here, too.
  */
  
  #ifndef SAMPLE_H
  #define SAMPLE_H
  
  /* mpg123lib_intern.h is included already, right? */
  
  /* Special case is fixed point math... which does work, but not that nice yet.  */
  #ifdef REAL_IS_FIXED
  static inline short idiv_signed_rounded(long x, int shift)
  {
  	x >>= (shift - 1);
  	x += (x & 1);
  	return (short)(x >> 1);
  }
  #  define REAL_PLUS_32767       ( 32767 << 15 )
  #  define REAL_MINUS_32768      ( -32768 << 15 )
  #  define REAL_TO_SHORT(x)      (idiv_signed_rounded(x, 15))
  /* No better code (yet).  */
  #  define REAL_TO_SHORT_ACCURATE(x) REAL_TO_SHORT(x)
  /* This is just here for completeness, it is not used! */
  # define REAL_TO_S32(x)        (x)
  #endif
  
  /* From now on for single precision float... double precision is a possible option once we added some bits. But, it would be rather insane. */
  #ifndef REAL_TO_SHORT
  
  /* Define the accurate rounding function. */
  # if (defined REAL_IS_FLOAT) && (defined IEEE_FLOAT)
  /* This function is only available for IEEE754 single-precision values
     This is nearly identical to proper rounding, just -+0.5 is rounded to 0 */
  static inline short ftoi16(float x)
  {
  	union
  	{
  		float f;
  		int32_t i;
  	} u_fi;
  	u_fi.f = x + 12582912.0f; /* Magic Number: 2^23 + 2^22 */
  	return (short)u_fi.i;
  }
  #  define REAL_TO_SHORT_ACCURATE(x)      ftoi16(x)
  # else
  /* The "proper" rounding, plain C, a bit slow. */
  #  define REAL_TO_SHORT_ACCURATE(x)      (short)((x)>0.0?(x)+0.5:(x)-0.5)
  # endif
  
  /* Now define the normal rounding. */
  # ifdef ACCURATE_ROUNDING
  #  define REAL_TO_SHORT(x)      REAL_TO_SHORT_ACCURATE(x)
  # else
  /* Non-accurate rounding... simple truncation. Fastest, most LSB errors. */
  #  define REAL_TO_SHORT(x)      (short)(x)
  # endif
  
  #endif /* REAL_TO_SHORT */
  
  /* We should add dithering for S32, too? */
  #ifndef REAL_TO_S32
  # ifdef ACCURATE_ROUNDING
  #  define REAL_TO_S32(x) (int32_t)((x)>0.0?(x)+0.5:(x)-0.5)
  # else
  #  define REAL_TO_S32(x) (int32_t)(x)
  # endif
  #endif
  
  #ifndef REAL_PLUS_32767
  # define REAL_PLUS_32767 32767.0
  #endif
  #ifndef REAL_MINUS_32768
  # define REAL_MINUS_32768 -32768.0
  #endif
  #ifndef REAL_PLUS_S32
  # define REAL_PLUS_S32 2147483647.0
  #endif
  #ifndef REAL_MINUS_S32
  # define REAL_MINUS_S32 -2147483648.0
  #endif
  
  
  /* The actual storage of a decoded sample is separated in the following macros.
     We can handle different types, we could also handle dithering here. */
  
  #ifdef NEWOLD_WRITE_SAMPLE
  
  /* This is the old new mpg123 WRITE_SAMPLE, fixed for newer GCC by MPlayer folks.
     Makes a huge difference on old machines. */
  #if WORDS_BIGENDIAN 
  #define MANTISSA_OFFSET 1
  #else
  #define MANTISSA_OFFSET 0
  #endif
  #define WRITE_SHORT_SAMPLE(samples,sum,clip) { \
    union { double dtemp; int itemp[2]; } u; int v; \
    u.dtemp = ((((65536.0 * 65536.0 * 16)+(65536.0 * 0.5))* 65536.0)) + (sum);\
    v = u.itemp[MANTISSA_OFFSET] - 0x80000000; \
    if( v > 32767) { *(samples) = 0x7fff; (clip)++; } \
    else if( v < -32768) { *(samples) = -0x8000; (clip)++; } \
    else { *(samples) = v; }  \
  }
  
  #else
  /* Macro to produce a short (signed 16bit) output sample from internal representation,
     which may be float, double or indeed some integer for fixed point handling. */
  #define WRITE_SHORT_SAMPLE(samples,sum,clip) \
    if( (sum) > REAL_PLUS_32767) { *(samples) = 0x7fff; (clip)++; } \
    else if( (sum) < REAL_MINUS_32768) { *(samples) = -0x8000; (clip)++; } \
    else { *(samples) = REAL_TO_SHORT(sum); }
  #endif
  
  /* Same as above, but always using accurate rounding. Would we want softer clipping here, too? */
  #define WRITE_SHORT_SAMPLE_ACCURATE(samples,sum,clip) \
    if( (sum) > REAL_PLUS_32767) { *(samples) = 0x7fff; (clip)++; } \
    else if( (sum) < REAL_MINUS_32768) { *(samples) = -0x8000; (clip)++; } \
    else { *(samples) = REAL_TO_SHORT_ACCURATE(sum); }
  
  /*
  	32bit signed 
  	We do clipping with the same old borders... but different conversion.
  	We see here that we need extra work for non-16bit output... we optimized for 16bit.
  	-0x7fffffff-1 is the minimum 32 bit signed integer value expressed so that MSVC 
  	does not give a compile time warning.
  */
  #define WRITE_S32_SAMPLE(samples,sum,clip) \
  	{ \
  		real tmpsum = REAL_MUL((sum),S32_RESCALE); \
  		if( tmpsum > REAL_PLUS_S32 ){ *(samples) = 0x7fffffff; (clip)++; } \
  		else if( tmpsum < REAL_MINUS_S32 ) { *(samples) = -0x7fffffff-1; (clip)++; } \
  		else { *(samples) = REAL_TO_S32(tmpsum); } \
  	}
  
  /* Produce an 8bit sample, via 16bit intermediate. */
  #define WRITE_8BIT_SAMPLE(samples,sum,clip) \
  { \
  	short write_8bit_tmp; \
  	if( (sum) > REAL_PLUS_32767) { write_8bit_tmp = 0x7fff; (clip)++; } \
  	else if( (sum) < REAL_MINUS_32768) { write_8bit_tmp = -0x8000; (clip)++; } \
  	else { write_8bit_tmp = REAL_TO_SHORT(sum); } \
  	*(samples) = fr->conv16to8[write_8bit_tmp>>AUSHIFT]; \
  }
  #ifndef REAL_IS_FIXED
  #define WRITE_REAL_SAMPLE(samples,sum,clip) *(samples) = ((real)1./SHORT_SCALE)*(sum)
  #endif
  
  #endif
  