diff options
author | Kenta Murata <mrkn@mrkn.jp> | 2021-01-12 22:58:17 +0900 |
---|---|---|
committer | Kenta Murata <mrkn@mrkn.jp> | 2021-01-13 02:11:18 +0900 |
commit | 4ba3a4491e15ed50f26c8f7a602fb4ef5452085a (patch) | |
tree | 1acc0f040522a8db6bc9a73dc996afa9c7dbfd7f /ext/bigdecimal/bigdecimal.c | |
parent | 2175c2c957a711f1c48f42d38db202bf52c8bc6f (diff) |
[ruby/bigdecimal] Optimize rb_float_convert_to_BigDecimal by using dtoa
This improve the conversion speed several times faster than before.
```
RUBYLIB= BUNDLER_ORIG_RUBYLIB= /home/mrkn/.rbenv/versions/3.0.0/bin/ruby -v -S benchmark-driver /home/mrkn/src/github.com/ruby/bigdecimal/benchmark/from_float.yml
ruby 3.0.0p0 (2020-12-25 revision 95aff21468) [x86_64-linux]
Calculating -------------------------------------
bigdecimal 3.0.0 master
flt_e0 156.400k 783.356k i/s - 100.000k times in 0.639388s 0.127656s
flt_ep10 158.640k 777.978k i/s - 100.000k times in 0.630359s 0.128538s
flt_ep100 101.676k 504.259k i/s - 100.000k times in 0.983512s 0.198311s
flt_em10 103.439k 726.339k i/s - 100.000k times in 0.966751s 0.137677s
flt_em100 79.675k 651.446k i/s - 100.000k times in 1.255095s 0.153505s
Comparison:
flt_e0
master: 783355.6 i/s
bigdecimal 3.0.0: 156399.5 i/s - 5.01x slower
flt_ep10
master: 777977.6 i/s
bigdecimal 3.0.0: 158639.7 i/s - 4.90x slower
flt_ep100
master: 504259.4 i/s
bigdecimal 3.0.0: 101676.5 i/s - 4.96x slower
flt_em10
master: 726338.6 i/s
bigdecimal 3.0.0: 103439.2 i/s - 7.02x slower
flt_em100
master: 651446.3 i/s
bigdecimal 3.0.0: 79675.3 i/s - 8.18x slower
```
https://github.com/ruby/bigdecimal/commit/5bdaedd530
https://github.com/ruby/bigdecimal/commit/9bfff57f90
https://github.com/ruby/bigdecimal/commit/d071a0abbb
Diffstat (limited to 'ext/bigdecimal/bigdecimal.c')
-rw-r--r-- | ext/bigdecimal/bigdecimal.c | 117 |
1 files changed, 114 insertions, 3 deletions
diff --git a/ext/bigdecimal/bigdecimal.c b/ext/bigdecimal/bigdecimal.c index 4997487572..2d3f09d562 100644 --- a/ext/bigdecimal/bigdecimal.c +++ b/ext/bigdecimal/bigdecimal.c @@ -74,7 +74,7 @@ static ID id_half; #define BASE1 (BASE/10) #ifndef DBLE_FIG -#define DBLE_FIG rmpd_double_figures() /* figure of double */ +#define DBLE_FIG RMPD_DOUBLE_FIGURES /* figure of double */ #endif #define LOG10_2 0.3010299956639812 @@ -205,6 +205,7 @@ cannot_be_coerced_into_BigDecimal(VALUE exc_class, VALUE v) } static inline VALUE BigDecimal_div2(VALUE, VALUE, VALUE); +static VALUE rb_inum_convert_to_BigDecimal(VALUE val, size_t digs, int raise_exception); static VALUE rb_float_convert_to_BigDecimal(VALUE val, size_t digs, int raise_exception); static VALUE rb_rational_convert_to_BigDecimal(VALUE val, size_t digs, int raise_exception); static VALUE rb_cstr_convert_to_BigDecimal(const char *c_str, size_t digs, int raise_exception); @@ -2824,8 +2825,118 @@ rb_float_convert_to_BigDecimal(VALUE val, size_t digs, int raise_exception) rb_raise(rb_eArgError, "precision too large."); } - val = rb_funcall(val, id_to_r, 0); - return rb_rational_convert_to_BigDecimal(val, digs, raise_exception); + /* Use the same logic in flo_to_s to convert a float to a decimal string */ + char buf[DBLE_FIG + BASE_FIG + 2 + 1]; + int decpt, negative_p; + char *e; + char *p = BigDecimal_dtoa(d, 2, digs, &decpt, &negative_p, &e); + int len10 = (int)(e - p); + if (len10 >= (int)sizeof(buf)) + len10 = (int)sizeof(buf) - 1; + memcpy(buf, p, len10); + xfree(p); + + VALUE inum; + size_t RB_UNUSED_VAR(prec) = 0; + size_t exp = 0; + if (decpt > 0) { + if (decpt < len10) { + /* + * len10 |---------------| + * : |-------| frac_len10 = len10 - decpt + * decpt |-------| |--| ntz10 = BASE_FIG - frac_len10 % BASE_FIG + * : : : + * 00 dd dddd.dddd dd 00 + * prec |-----.----.----.-----| prec = exp + roomof(frac_len, BASE_FIG) + * exp |-----.----| exp = roomof(decpt, BASE_FIG) + */ + const size_t frac_len10 = len10 - decpt; + const size_t ntz10 = BASE_FIG - frac_len10 % BASE_FIG; + memset(buf + len10, '0', ntz10); + buf[len10 + ntz10] = '\0'; + inum = rb_cstr_to_inum(buf, 10, false); + + exp = roomof(decpt, BASE_FIG); + prec = exp + roomof(frac_len10, BASE_FIG); + } + else { + /* + * decpt |-----------------------| + * len10 |----------| : + * : |------------| exp10 + * : : : + * 00 dd dddd dd 00 0000 0000.0 + * : : : : + * : |--| ntz10 = exp10 % BASE_FIG + * prec |-----.----.-----| : + * : |----.----| exp10 / BASE_FIG + * exp |-----.----.-----.----.----| + */ + const size_t exp10 = decpt - len10; + const size_t ntz10 = exp10 % BASE_FIG; + + memset(buf + len10, '0', ntz10); + buf[len10 + ntz10] = '\0'; + inum = rb_cstr_to_inum(buf, 10, false); + + prec = roomof(len10 + ntz10, BASE_FIG); + exp = prec + exp10 / BASE_FIG; + } + } + else if (decpt == 0) { + /* + * len10 |------------| + * : : + * 0.dddd dddd dd 00 + * : : : + * : |--| ntz10 = prec * BASE_FIG - len10 + * prec |----.----.-----| roomof(len10, BASE_FIG) + */ + prec = roomof(len10, BASE_FIG); + const size_t ntz10 = prec * BASE_FIG - len10; + + memset(buf + len10, '0', ntz10); + buf[len10 + ntz10] = '\0'; + inum = rb_cstr_to_inum(buf, 10, false); + } + else { + /* + * len10 |---------------| + * : : + * decpt |-------| |--| ntz10 = prec * BASE_FIG - nlz10 - len10 + * : : : + * 0.0000 00 dd dddd dddd dd 00 + * : : : + * nlz10 |--| : decpt % BASE_FIG + * prec |-----.----.----.-----| roomof(decpt + len10, BASE_FIG) - exp + * exp |----| decpt / BASE_FIG + */ + decpt = -decpt; + + const size_t nlz10 = decpt % BASE_FIG; + exp = decpt / BASE_FIG; + prec = roomof(decpt + len10, BASE_FIG) - exp; + const size_t ntz10 = prec * BASE_FIG - nlz10 - len10; + + if (nlz10 > 0) { + memmove(buf + nlz10, buf, len10); + memset(buf, '0', nlz10); + } + memset(buf + nlz10 + len10, '0', ntz10); + buf[nlz10 + len10 + ntz10] = '\0'; + inum = rb_cstr_to_inum(buf, 10, false); + + exp = -exp; + } + + VALUE bd = rb_inum_convert_to_BigDecimal(inum, SIZE_MAX, raise_exception); + Real *vp; + TypedData_Get_Struct(bd, Real, &BigDecimal_data_type, vp); + assert(vp->Prec == prec); + vp->exponent = exp; + + if (negative_p) VpSetSign(vp, -1); + return bd; } static VALUE |