Welcome! Log In Create A New Profile

Advanced

[njs] Improved naming in njs_dtoa() internal functions.

Dmitry Volyntsev
October 03, 2019 10:00AM
details: https://hg.nginx.org/njs/rev/cb7874a63d2b
branches:
changeset: 1168:cb7874a63d2b
user: Dmitry Volyntsev <xeioex@nginx.com>
date: Thu Oct 03 16:26:04 2019 +0300
description:
Improved naming in njs_dtoa() internal functions.

diffstat:

src/njs_dtoa.c | 127 +++++++++++++++++++++++++++-----------------------------
src/njs_dtoa.h | 2 +-
2 files changed, 63 insertions(+), 66 deletions(-)

diffs (242 lines):

diff -r 5f0812d53158 -r cb7874a63d2b src/njs_dtoa.c
--- a/src/njs_dtoa.c Thu Oct 03 15:41:30 2019 +0300
+++ b/src/njs_dtoa.c Thu Oct 03 16:26:04 2019 +0300
@@ -40,14 +40,14 @@


njs_inline void
-njs_grisu2_round(char *start, size_t len, uint64_t delta, uint64_t rest,
- uint64_t ten_kappa, uint64_t wp_w)
+njs_round(char *start, size_t length, uint64_t delta, uint64_t rest,
+ uint64_t ten_kappa, uint64_t margin)
{
- while (rest < wp_w && delta - rest >= ten_kappa
- && (rest + ten_kappa < wp_w || /* closer */
- wp_w - rest > rest + ten_kappa - wp_w))
+ while (rest < margin && delta - rest >= ten_kappa
+ && (rest + ten_kappa < margin || /* closer */
+ margin - rest > rest + ten_kappa - margin))
{
- start[len - 1]--;
+ start[length - 1]--;
rest += ten_kappa;
}
}
@@ -81,14 +81,14 @@ njs_dec_count(uint32_t n)


njs_inline size_t
-njs_grisu2_gen(njs_diyfp_t W, njs_diyfp_t Mp, uint64_t delta, char *start,
+njs_digit_gen(njs_diyfp_t v, njs_diyfp_t high, uint64_t delta, char *start,
int *dec_exp)
{
int kappa;
- char c, *p;
- uint32_t p1, d;
- uint64_t p2, tmp;
- njs_diyfp_t one, wp_w;
+ char *p;
+ uint32_t integer, d;
+ uint64_t fraction, rest, margin;
+ njs_diyfp_t one;

static const uint64_t pow10[] = {
1,
@@ -103,34 +103,29 @@ njs_grisu2_gen(njs_diyfp_t W, njs_diyfp_
1000000000
};

- wp_w = njs_diyfp_sub(Mp, W);
+ one = njs_diyfp((uint64_t) 1 << -high.exp, high.exp);
+ integer = (uint32_t) (high.significand >> -one.exp);
+ fraction = high.significand & (one.significand - 1);

- one = njs_diyfp((uint64_t) 1 << -Mp.exp, Mp.exp);
- p1 = (uint32_t) (Mp.significand >> -one.exp);
- p2 = Mp.significand & (one.significand - 1);
+ margin = njs_diyfp_sub(high, v).significand;

p = start;

- /* GCC 4.2 complains about uninitialized d. */
- d = 0;
-
- kappa = njs_dec_count(p1);
+ kappa = njs_dec_count(integer);

while (kappa > 0) {

switch (kappa) {
- case 10: d = p1 / 1000000000; p1 %= 1000000000; break;
- case 9: d = p1 / 100000000; p1 %= 100000000; break;
- case 8: d = p1 / 10000000; p1 %= 10000000; break;
- case 7: d = p1 / 1000000; p1 %= 1000000; break;
- case 6: d = p1 / 100000; p1 %= 100000; break;
- case 5: d = p1 / 10000; p1 %= 10000; break;
- case 4: d = p1 / 1000; p1 %= 1000; break;
- case 3: d = p1 / 100; p1 %= 100; break;
- case 2: d = p1 / 10; p1 %= 10; break;
- case 1: d = p1; p1 = 0; break;
- default:
- njs_unreachable();
+ case 10: d = integer / 1000000000; integer %= 1000000000; break;
+ case 9: d = integer / 100000000; integer %= 100000000; break;
+ case 8: d = integer / 10000000; integer %= 10000000; break;
+ case 7: d = integer / 1000000; integer %= 1000000; break;
+ case 6: d = integer / 100000; integer %= 100000; break;
+ case 5: d = integer / 10000; integer %= 10000; break;
+ case 4: d = integer / 1000; integer %= 1000; break;
+ case 3: d = integer / 100; integer %= 100; break;
+ case 2: d = integer / 10; integer %= 10; break;
+ default: d = integer; integer = 0; break;
}

if (d != 0 || p != start) {
@@ -139,12 +134,12 @@ njs_grisu2_gen(njs_diyfp_t W, njs_diyfp_

kappa--;

- tmp = ((uint64_t) p1 << -one.exp) + p2;
+ rest = ((uint64_t) integer << -one.exp) + fraction;

- if (tmp <= delta) {
+ if (rest < delta) {
*dec_exp += kappa;
- njs_grisu2_round(start, p - start, delta, tmp,
- pow10[kappa] << -one.exp, wp_w.significand);
+ njs_round(start, p - start, delta, rest, pow10[kappa] << -one.exp,
+ margin);
return p - start;
}
}
@@ -152,27 +147,26 @@ njs_grisu2_gen(njs_diyfp_t W, njs_diyfp_
/* kappa = 0. */

for ( ;; ) {
- p2 *= 10;
+ fraction *= 10;
delta *= 10;
- c = (char) (p2 >> -one.exp);
+
+ d = (uint32_t) (fraction >> -one.exp);

- if (c != 0 || p != start) {
- *p++ = '0' + c;
+ if (d != 0 || p != start) {
+ *p++ = '0' + d;
}

- p2 &= one.significand - 1;
+ fraction &= one.significand - 1;
kappa--;

- if (p2 < delta) {
+ if (fraction < delta) {
*dec_exp += kappa;
- tmp = (-kappa < 10) ? pow10[-kappa] : 0;
- njs_grisu2_round(start, p - start, delta, p2, one.significand,
- wp_w.significand * tmp);
- break;
+ margin *= (-kappa < 10) ? pow10[-kappa] : 0;
+ njs_round(start, p - start, delta, fraction, one.significand,
+ margin);
+ return p - start;
}
}
-
- return p - start;
}


@@ -212,26 +206,31 @@ njs_diyfp_normalize_boundaries(njs_diyfp
}


+/*
+ * Grisu2 produces optimal (shortest) decimal representation for 99.8%
+ * of IEEE doubles. For remaining 0.2% bignum algorithm like Dragon4 is requred.
+ */
njs_inline size_t
njs_grisu2(double value, char *start, int *dec_exp)
{
- njs_diyfp_t v, w_m, w_p, c_mk, W, Wp, Wm;
+ njs_diyfp_t v, low, high, ten_mk, scaled_v, scaled_low, scaled_high;

v = njs_d2diyfp(value);

- njs_diyfp_normalize_boundaries(v, &w_m, &w_p);
+ njs_diyfp_normalize_boundaries(v, &low, &high);

- c_mk = njs_cached_power_bin(w_p.exp, dec_exp);
- W = njs_diyfp_mul(njs_diyfp_normalize(v), c_mk);
+ ten_mk = njs_cached_power_bin(high.exp, dec_exp);

- Wp = njs_diyfp_mul(w_p, c_mk);
- Wm = njs_diyfp_mul(w_m, c_mk);
+ scaled_v = njs_diyfp_mul(njs_diyfp_normalize(v), ten_mk);
+ scaled_low = njs_diyfp_mul(low, ten_mk);
+ scaled_high = njs_diyfp_mul(high, ten_mk);

- Wm.significand++;
- Wp.significand--;
+ scaled_low.significand++;
+ scaled_high.significand--;

- return njs_grisu2_gen(W, Wp, Wp.significand - Wm.significand, start,
- dec_exp);
+ return njs_digit_gen(scaled_v, scaled_high,
+ scaled_high.significand - scaled_low.significand,
+ start, dec_exp);
}


@@ -239,7 +238,7 @@ njs_inline size_t
njs_write_exponent(int exp, char *start)
{
char *p;
- size_t len;
+ size_t length;
uint32_t u32;
char buf[4];

@@ -261,16 +260,16 @@ njs_write_exponent(int exp, char *start)
u32 /= 10;
} while (u32 != 0);

- len = buf + njs_length(buf) - p;
+ length = buf + njs_length(buf) - p;

- memcpy(start, p, len);
+ memcpy(start, p, length);

- return len + 1;
+ return length + 1;
}


njs_inline size_t
-njs_prettify(char *start, size_t len, int dec_exp)
+njs_dtoa_format(char *start, size_t len, int dec_exp)
{
int kk, offset, length;
size_t size;
@@ -365,7 +364,5 @@ njs_dtoa(double value, char *start)

length = njs_grisu2(value, p, &dec_exp);

- length = njs_prettify(p, length, dec_exp);
-
- return minus + length;
+ return njs_dtoa_format(p, length, dec_exp) + minus;
}
diff -r 5f0812d53158 -r cb7874a63d2b src/njs_dtoa.h
--- a/src/njs_dtoa.h Thu Oct 03 15:41:30 2019 +0300
+++ b/src/njs_dtoa.h Thu Oct 03 16:26:04 2019 +0300
@@ -7,6 +7,6 @@
#ifndef _NJS_DTOA_H_INCLUDED_
#define _NJS_DTOA_H_INCLUDED_

-NJS_EXPORT size_t njs_dtoa(double value, char *buffer);
+NJS_EXPORT size_t njs_dtoa(double value, char *start);

#endif /* _NJS_DTOA_H_INCLUDED_ */
_______________________________________________
nginx-devel mailing list
nginx-devel@nginx.org
http://mailman.nginx.org/mailman/listinfo/nginx-devel
Subject Author Views Posted

[njs] Improved naming in njs_dtoa() internal functions.

Dmitry Volyntsev 70 October 03, 2019 10:00AM



Sorry, you do not have permission to post/reply in this forum.

Online Users

Guests: 103
Record Number of Users: 6 on February 13, 2018
Record Number of Guests: 421 on December 02, 2018
Powered by nginx      Powered by FreeBSD      PHP Powered      Powered by MariaDB      ipv6 ready