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https://git.planet-casio.com/Vhex-Kernel-Core/fxlibc.git
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95 lines
3 KiB
C
95 lines
3 KiB
C
/*
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Copyright (c) 2009 Florian Loitsch
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Permission is hereby granted, free of charge, to any person
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obtaining a copy of this software and associated documentation
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files (the "Software"), to deal in the Software without
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restriction, including without limitation the rights to use,
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copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the
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Software is furnished to do so, subject to the following
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conditions:
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The above copyright notice and this permission notice shall be
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included in all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include "diy_fp.h"
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#include "k_comp.h"
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#include "double.h"
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#include "powers.h"
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#include <stdbool.h>
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#include "grisu2.h"
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#include <stdint.h>
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#define TEN9 1000000000
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void grisu_round(char* buffer, int len,
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uint64_t delta, uint64_t rest,
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uint64_t ten_kappa, uint64_t wp_w) {
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while (rest < wp_w &&
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delta - rest >= ten_kappa &&
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(rest + ten_kappa < wp_w || /// closer
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wp_w - rest > rest+ten_kappa - wp_w))
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{
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buffer[len-1]--; rest += ten_kappa;
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}
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}
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void digit_gen(diy_fp_t W, diy_fp_t Mp, diy_fp_t delta,
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char* buffer, int* len, int* K) {
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uint32_t div; int d,kappa; diy_fp_t one, wp_w;
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wp_w = minus(Mp, W);
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one.f = ((uint64_t) 1) << -Mp.e; one.e = Mp.e;
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uint32_t p1 = Mp.f >> -one.e; /// Mp_cut
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uint64_t p2 = Mp.f & (one.f - 1);
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*len = 0; kappa = 10; div = TEN9;
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while (kappa > 0) {
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d = p1 / div;
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if (d || *len) buffer[(*len)++] = '0' + d; /// Mp_inv1
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p1 %= div; kappa--;
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uint64_t tmp = (((uint64_t)p1)<<-one.e)+p2;
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if (tmp <= delta.f) { /// Mp_delta
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*K += kappa;
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grisu_round(buffer, *len, delta.f, tmp, ((uint64_t)div) << -one.e, wp_w.f);
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return;
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}
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div /= 10;
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}
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uint64_t unit = 1;
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while (1) {
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p2 *= 10; delta.f *= 10; unit *= 10;
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d = p2 >> -one.e;
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if (d || *len) buffer[(*len)++] = '0' + d;
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p2 &= one.f - 1; kappa--;
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if (p2 < delta.f) {
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*K += kappa;
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grisu_round(buffer, *len, delta.f, p2, one.f, wp_w.f*unit);
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return;
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}
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}
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}
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void grisu2(double v, char* buffer, int* length, int* K) {
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diy_fp_t w_m, w_p;
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int q = 64, alpha = -59, gamma = -56; int pos;
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normalized_boundaries(v, &w_m, &w_p);
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diy_fp_t w = normalize_diy_fp(double2diy_fp(v));
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int mk = k_comp(w_p.e + q, alpha, gamma);
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diy_fp_t c_mk = cached_power(mk);
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diy_fp_t W = multiply(w, c_mk);
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diy_fp_t Wp = multiply(w_p, c_mk);
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diy_fp_t Wm = multiply(w_m, c_mk);
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Wm.f++; Wp.f--;
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diy_fp_t delta = minus(Wp, Wm);
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*K = -mk;
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digit_gen(W, Wp, delta, buffer, length, K);
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}
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