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55 lines
1.5 KiB
C
55 lines
1.5 KiB
C
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#ifndef _FLOAT_H_
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#define _FLOAT_H_
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/* ieee754 32bit format:
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*
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* sign
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* / /exponent/mantissa
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* 3 32222222 22211111111110000000000
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* 1 09876543 21098765432109876543210
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*
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* The sign is stored in bit 31.
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* The exponent can be computed from bits 23-30 by subtracting 127. (128 = 2^1)
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* The mantissa is stored in bits 0-22.
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* An invisible leading bit (i.e. it is not actually stored) with value 1.0
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* is placed in front, then bit 23 has a value of 1/2, bit 22 has value 1/4 etc.
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* As a result, the mantissa has a value between 1.0 and 2.
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*
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* 1.0 = exp=127, mantissa=0
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*
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* If the exponent reaches -127 (binary 00000000), the leading 1 is no longer
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* used to enable gradual underflow.
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*
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*/
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typedef struct {
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unsigned char exponent; /* msb is the sign */
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unsigned char mantissa[3]; /* msb is lsb of exponent */
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} FLOAT754;
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/* we dont wanna seriously use double precision eh? ;=P */
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/* #define double float */
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/* string to/from float conversion functions */
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char *_ftoa(char *buf, float n);
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/* string conversion functions, these use the exponential form */
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char * __fastcall__ _ftostr(char *d, float s); /* for vsprintf */
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float __fastcall__ _strtof(char *d);
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/* beware, this is not standard */
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#ifndef M_PI
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#define M_PI 3.14159265358979323846f
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#endif
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/* degrees to radiants */
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#define deg2rad(_fs, _n) ((_fs / _n) * (2.0f * M_PI))
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/* radiants to degrees deg = (rad / (2 * pi)) * 256 */
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#define rad2deg(_rad, _n) ((_rad / (2.0f * M_PI)) * _n)
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/* resets fp-libs in Turbo-C and M$-C */
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#define _fpreset()
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#endif /* _FLOAT_H_ */
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