mangle.h File Reference

Go to the source code of this file.

Macros
#define	BITMASK(bits)   ( (1<<bits)-1 )
#define	SIGN_MASK   0x80000000
#define	EXP_MASK   0x7f800000
#define	SIGNIF_MASK   0x007fffff
#define	EXP_BITS   8
#define	SIGNIF_BITS   23

Functions
unsigned int	float_to_uint32 (float value, char exponent, char significand, char denorm)
float	uint32_to_float (unsigned int value, char exponent, char significand, char denorm)

Macro Definition Documentation

#define BITMASK

(

bits)

( (1<<bits)-1 )

Definition at line 22 of file mangle.h.

Referenced by float_to_uint32(), and uint32_to_float().

#define EXP_BITS   8

Definition at line 26 of file mangle.h.

Referenced by float_to_uint32().

#define EXP_MASK   0x7f800000

Definition at line 24 of file mangle.h.

Referenced by float_to_uint32().

#define SIGN_MASK   0x80000000

Definition at line 23 of file mangle.h.

Referenced by float_to_uint32().

#define SIGNIF_BITS   23

Definition at line 27 of file mangle.h.

Referenced by float_to_uint32(), and uint32_to_float().

#define SIGNIF_MASK   0x007fffff

Definition at line 25 of file mangle.h.

Referenced by float_to_uint32().

Function Documentation

unsigned int float_to_uint32	(	float	value,
		char	exponent,
		char	significand,
		char	denorm
	)

Definition at line 54 of file mangle.cpp.

References BITMASK, EXP_BITS, EXP_MASK, type_conv::fl_val, SIGN_MASK, SIGNIF_BITS, SIGNIF_MASK, and type_conv::u32_val.

{
    union type_conv tmp;
    unsigned int    newval, tmpsig;
    int tmpexp;

    tmp.fl_val = value;
    //set the sign bit
    newval     = SIGN_MASK&tmp.u32_val;
    newval   >>= EXP_BITS+SIGNIF_BITS-(exponent+significand);
    //get the exponent and remove its offset
    tmpexp     = (EXP_MASK&tmp.u32_val)>>SIGNIF_BITS;
    tmpexp    -= 127;
    //get the significand but leave one extra bit for use while performing
    //rounding later
    tmpsig     = (SIGNIF_MASK&tmp.u32_val)>>(SIGNIF_BITS-significand-1);
    //if this will be a normalized number, perform rounding
    if (tmpexp > denorm && tmpsig&1) {
        tmpsig++;
        if ( tmpsig&( 1<<(significand+1) ) ) {
            tmpexp++;
            tmpsig -= 1<<(significand+1);
        }
    }
    //remove the bit saved for rounding
    tmpsig >>= 1;
    if (tmpexp == denorm) {
        if (tmpsig&1)          //more rounding fun
            tmpsig++;
        if ( tmpsig&(1<<significand) ) {
            tmpexp++;
            tmpsig -= 1<<significand;
            tmpexp  = 1;
        } else {
            tmpsig  |= 1<<significand;
            tmpsig >>= 1;
            tmpexp   = 0;
        }
    } else if (tmpexp < denorm) {
        tmpsig  |= 1<<significand;
        tmpsig >>= denorm-tmpexp;
        if (tmpsig&1)
            tmpsig++;
        tmpsig >>= 1;
        tmpexp   = 0;
        //if the number is too big, clamp it to the maximum represented value
    } else if (tmpexp >= (1<<exponent)+denorm) {
        tmpexp = BITMASK( exponent );
        tmpsig = BITMASK( significand );
    } else {
        tmpexp -= denorm;
    }
    newval |= (tmpexp<<significand)|tmpsig;
    return newval;
}

float uint32_to_float	(	unsigned int	value,
		char	exponent,
		char	significand,
		char	denorm
	)

Definition at line 110 of file mangle.cpp.

References BITMASK, type_conv::fl_val, SIGNIF_BITS, and type_conv::u32_val.

{
    union type_conv newval;
    unsigned int    tmpsig;
    int tmpexp;

    newval.u32_val   = ( 1<<(exponent+significand) )&value;
    newval.u32_val <<= 31-(exponent+significand);
    tmpsig   = value&BITMASK( significand );
    tmpexp   = value&(BITMASK( exponent )<<significand);
    tmpexp >>= significand;
    //if the number should be 0 or -0, go ahead and return
    if (tmpexp == 0 && tmpsig == 0) {
        return newval.fl_val;
        //if a denormalized value, rebuild to normalized form
    } else if (tmpexp == 0) {
        tmpsig <<= 1;
        while ( !( tmpsig&(1<<significand) ) ) {
            tmpexp  -= 1;
            tmpsig <<= 1;
        }
        tmpsig -= 1<<significand;
    }
    tmpexp  += 127+denorm;
    tmpsig <<= SIGNIF_BITS-significand;

    newval.u32_val |= tmpexp<<SIGNIF_BITS;
    newval.u32_val |= tmpsig;

    return newval.fl_val;
}