d351995294
- need to change to have implicit decimal point after first digit - need to rework for code size
62 lines
1.6 KiB
C
62 lines
1.6 KiB
C
/*
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* decn.h
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*
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* Created on: Mar 21, 2019
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*/
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#ifndef SRC_DEC_DECN_H_
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#define SRC_DEC_DECN_H_
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#include <stdint.h>
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#define DEC64_NUM_LSU 8
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#define DEC80_NUM_LSU 10
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//follow IEEE754 standard
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#define DEC64_MIN_EXP (-383)
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#define DEC64_MAX_EXP (384)
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//allow full range, but reserve -16384 for special numbers
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#define DEC80_MIN_EXP (-16383)
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#define DEC80_MAX_EXP 16383
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//decimal64 unpacked into 72 bits
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typedef struct {
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int16_t exponent;
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uint8_t lsu[DEC64_NUM_LSU]; //lus[0] holds most-significant 2 nibbles
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} dec64;
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//decimal80 unpacked into 80 bits
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// for computation
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typedef struct {
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int16_t exponent; //MSBit is sign of dec80 number, bottom 15 bits are 2's Compl exponent
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uint8_t lsu[DEC80_NUM_LSU]; //lus[0] holds most-significant 2 nibbles
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} dec80;
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//remove sign bit, and return 15 bit exponent sign-extended to 16 bits
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int16_t get_exponent(const dec80* x);
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void dec64to80(dec80* dest, const dec64* src);
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void dec80to64(dec64* dest, const dec80* src);
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void copy_decn(dec80* dest, const dec80* src);
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void build_dec64(dec64* dest, const char* signif_str, int16_t exponent);
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//void build_dec80(dec80* dest, const char* signif_str, int16_t exponent);
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void set_dec64_zero(dec64* dest);
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void set_dec80_zero(dec80* dest);
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void set_dec64_NaN(dec64* dest);
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void set_dec80_NaN(dec80* dest);
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void negate_decn(dec80* x);
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int8_t compare_decn(dec80* a, dec80* b); //a<b: -1, a==b: 0, a>b: 1
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void add_decn(dec80* acc, const dec80* x);
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//buf should hold at least 18 + 4 + 5 + 1 = 28
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#define DECN_BUF_SIZE 28
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void dec80_to_str(char* buf, const dec80* x);
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void dec64_to_str(char* buf, const dec64* x);
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#endif /* SRC_DEC_DECN_H_ */
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