58 lines
2.5 KiB
C
58 lines
2.5 KiB
C
/* ************************************************************************** */
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/* _____ _ */
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/* libg1m/bcd.h |_ _|__ _ _| |__ ___ _ _ */
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/* | Project: libg1m | |/ _ \| | | | '_ \ / _ \ | | | */
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/* | | (_) | |_| | | | | __/ |_| | */
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/* By: thomas <thomas@touhey.fr> |_|\___/ \__,_|_| |_|\___|\__, |.fr */
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/* Last updated: 2016/11/21 09:23:44 |___/ */
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/* */
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/* ************************************************************************** */
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#ifndef LIBG1M_BCD_H
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# define LIBG1M_BCD_H
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/* ************************************************************************** */
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/* Type definition */
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/* ************************************************************************** */
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/* BCD are the main number format CASIO uses in its calculators.
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* Each semi-byte is a digit going from 0 to 9 (0xA to 0xF aren't used).
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* This format has the huge advantage to make 0.1 + 0.2 and 0.3 equal.
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*
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* The first three digits are the exponent.
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* If the exponent is more than 500, then remove 500, and that means the
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* number is negative.
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* Then you have to remove 100 to have the real exponent.
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*
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* The other 15 digits are the mantissa. So the number is: (0,M ** E) */
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struct bcd {
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/* the BCD value itself */
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unsigned char BCDval[9];
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/* some 4-bytes alignment stuff */
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unsigned char _align[3];
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};
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/* ************************************************************************** */
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/* BCD utilities */
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/* ************************************************************************** */
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/* Arithmetic */
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int g1m_bcd_is_nonzero(struct bcd *bcd);
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/* String/BCD */
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char *g1m_bcdtoa(struct bcd *bcd);
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/* ************************************************************************** */
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/* Inline BCD utilities */
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/* ************************************************************************** */
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/* check if BCD number is negative */
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static inline int g1m_bcd_is_negative(struct bcd *bcd)
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{
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return ((bcd->BCDval[0] & 0xf0) >= 0x50);
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}
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/* macros */
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# define g1m_bcd_is_positive(B) (~g1m_bcd_is_negative(B) & 1)
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# define g1m_bcd_is_zero(B) (!g1m_bcd_is_nonzero(B))
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#endif /* LIBG1M_BCD_H */
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