diff options
Diffstat (limited to 'ext/bigdecimal')
| -rw-r--r-- | ext/bigdecimal/bigdecimal.c | 201 |
1 files changed, 142 insertions, 59 deletions
diff --git a/ext/bigdecimal/bigdecimal.c b/ext/bigdecimal/bigdecimal.c index e0496c2d6e..fa7ae62f7f 100644 --- a/ext/bigdecimal/bigdecimal.c +++ b/ext/bigdecimal/bigdecimal.c @@ -319,86 +319,168 @@ BigDecimal_prec(VALUE self) return obj; } -/* - * call-seq: - * precision -> integer - * - * Returns the number of decimal digits in +self+: - * - * BigDecimal("0").precision # => 0 - * BigDecimal("1").precision # => 1 - * BigDecimal("-1e20").precision # => 21 - * BigDecimal("1e-20").precision # => 20 - * BigDecimal("Infinity").precision # => 0 - * BigDecimal("-Infinity").precision # => 0 - * BigDecimal("NaN").precision # => 0 - * - */ -static VALUE -BigDecimal_precision(VALUE self) +static void +BigDecimal_count_precision_and_scale(VALUE self, ssize_t *out_precision, ssize_t *out_scale) { ENTER(1); + if (out_precision == NULL && out_scale == NULL) + return; + Real *p; GUARD_OBJ(p, GetVpValue(self, 1)); - if (VpIsZero(p) || !VpIsDef(p)) return INT2FIX(0); + if (VpIsZero(p) || !VpIsDef(p)) { + zero: + if (out_precision) *out_precision = 0; + if (out_scale) *out_scale = 0; + return; + } + + DECDIG x; + + ssize_t n = p->Prec; /* The length of frac without zeros. */ + while (n > 0 && p->frac[n-1] == 0) --n; + if (n == 0) goto zero; + + int nlz = BASE_FIG; + for (x = p->frac[0]; x > 0; x /= 10) --nlz; + + int ntz = 0; + for (x = p->frac[n-1]; x > 0 && x % 10 == 0; x /= 10) ++ntz; /* - * The most significant digit is frac[0], and the least significant digit is frac[Prec-1]. - * When the exponent is zero, the decimal point is located just before frac[0]. + * Calculate the precision and the scale + * ------------------------------------- * + * The most significant digit is frac[0], and the least significant digit + * is frac[Prec-1]. When the exponent is zero, the decimal point is + * located just before frac[0]. * * When the exponent is negative, the decimal point moves to leftward. - * In this case, the precision can be calculated by BASE_FIG * (-exponent + Prec) - ntz. + * In this case, the precision can be calculated by + * + * precision = BASE_FIG * (-exponent + n) - ntz, + * + * and the scale is the same as precision. * - * 0 . 0000 0000 | frac[0] frac[1] ... frac[Prec-1] - * <----------| exponent == -2 + * 0 . 0000 0000 | frac[0] ... frac[n-1] | + * |<----------| exponent == -2 | + * |---------------------------------->| precision + * |---------------------------------->| scale * - * Conversely, when the exponent is positive, the decimal point moves to rightward. * - * | frac[0] frac[1] frac[2] . frac[3] frac[4] ... frac[Prec-1] - * |------------------------> exponent == 3 + * Conversely, when the exponent is positive, the decimal point moves to + * rightward. In this case, the scale equals to + * + * BASE_FIG * (n - exponent) - ntz. + * + * the precision equals to + * + * scale + BASE_FIG * exponent - nlz. + * + * | frac[0] frac[1] . frac[2] ... frac[n-1] | + * |---------------->| exponent == 2 | + * | |---------------------->| scale + * |---------------------------------------->| precision */ ssize_t ex = p->exponent; /* Count the number of decimal digits before frac[1]. */ - ssize_t precision = BASE_FIG; /* The number of decimal digits in frac[0]. */ + ssize_t n_digits_head = BASE_FIG; if (ex < 0) { - precision += -ex * BASE_FIG; /* The number of leading zeros before frac[0]. */ - ex = 0; + n_digits_head += (-ex) * BASE_FIG; /* The number of leading zeros before frac[0]. */ + ex = 0; } else if (ex > 0) { - /* Count the number of decimal digits without the leading zeros in - * the most significant digit in the integral part. */ - DECDIG x = p->frac[0]; - for (precision = 0; x > 0; x /= 10) { - ++precision; - } + /* Count the number of decimal digits without the leading zeros in + * the most significant digit in the integral part. + */ + n_digits_head -= nlz; /* Make the number of digits */ } - /* Count the number of decimal digits after frac[0]. */ - if (ex > (ssize_t)p->Prec) { - /* In this case the number is an integer with multiple trailing zeros. */ - precision += (ex - 1) * BASE_FIG; + if (out_precision) { + ssize_t precision = n_digits_head; + + /* Count the number of decimal digits after frac[0]. */ + if (ex > (ssize_t)n) { + /* In this case the number is an integer with some trailing zeros. */ + precision += (ex - 1) * BASE_FIG; + } + else if (n > 0) { + precision += (n - 1) * BASE_FIG; + + if (ex < (ssize_t)n) { + precision -= ntz; + } + } + + *out_precision = precision; } - else if (p->Prec > 0) { - ssize_t n = (ssize_t)p->Prec - 1; - while (n > 0 && p->frac[n] == 0) --n; /* Skip trailing zeros, just in case. */ - precision += n * BASE_FIG; + if (out_scale) { + ssize_t scale = 0; - if (ex < (ssize_t)p->Prec) { - DECDIG x = p->frac[n]; - for (; x > 0 && x % 10 == 0; x /= 10) { - --precision; - } + if (p->exponent < 0) { + scale = n_digits_head + (n - 1) * BASE_FIG - ntz; + } + else if (n > p->exponent) { + scale = (n - p->exponent) * BASE_FIG - ntz; } + + *out_scale = scale; } +} +/* + * call-seq: + * precision -> integer + * + * Returns the number of decimal digits in +self+: + * + * BigDecimal("0").precision # => 0 + * BigDecimal("1").precision # => 1 + * BigDecimal("1.1").precision # => 2 + * BigDecimal("3.1415").precision # => 5 + * BigDecimal("-1e20").precision # => 21 + * BigDecimal("1e-20").precision # => 20 + * BigDecimal("Infinity").precision # => 0 + * BigDecimal("-Infinity").precision # => 0 + * BigDecimal("NaN").precision # => 0 + * + */ +static VALUE +BigDecimal_precision(VALUE self) +{ + ssize_t precision; + BigDecimal_count_precision_and_scale(self, &precision, NULL); return SSIZET2NUM(precision); } +/* + * call-seq: + * scale -> integer + * + * Returns the number of decimal digits following the decimal digits in +self+. + * + * BigDecimal("0").scale # => 0 + * BigDecimal("1").scale # => 1 + * BigDecimal("1.1").scale # => 1 + * BigDecimal("3.1415").scale # => 4 + * BigDecimal("-1e20").precision # => 0 + * BigDecimal("1e-20").precision # => 20 + * BigDecimal("Infinity").scale # => 0 + * BigDecimal("-Infinity").scale # => 0 + * BigDecimal("NaN").scale # => 0 + */ +static VALUE +BigDecimal_scale(VALUE self) +{ + ssize_t scale; + BigDecimal_count_precision_and_scale(self, NULL, &scale); + return SSIZET2NUM(scale); +} + static VALUE BigDecimal_n_significant_digits(VALUE self) { @@ -406,23 +488,23 @@ BigDecimal_n_significant_digits(VALUE self) Real *p; GUARD_OBJ(p, GetVpValue(self, 1)); - - ssize_t n = p->Prec; - while (n > 0 && p->frac[n-1] == 0) --n; - if (n <= 0) { + if (VpIsZero(p) || !VpIsDef(p)) { return INT2FIX(0); } - int nlz, ntz; + ssize_t n = p->Prec; /* The length of frac without trailing zeros. */ + for (n = p->Prec; n > 0 && p->frac[n-1] == 0; --n); + if (n == 0) return INT2FIX(0); - DECDIG x = p->frac[0]; - for (nlz = BASE_FIG; x > 0; x /= 10) --nlz; + DECDIG x; + int nlz = BASE_FIG; + for (x = p->frac[0]; x > 0; x /= 10) --nlz; - x = p->frac[n-1]; - for (ntz = 0; x > 0 && x % 10 == 0; x /= 10) ++ntz; + int ntz = 0; + for (x = p->frac[n-1]; x > 0 && x % 10 == 0; x /= 10) ++ntz; - ssize_t n_digits = BASE_FIG * n - nlz - ntz; - return SSIZET2NUM(n_digits); + ssize_t n_significant_digits = BASE_FIG*n - nlz - ntz; + return SSIZET2NUM(n_significant_digits); } /* @@ -4129,6 +4211,7 @@ Init_bigdecimal(void) /* instance methods */ rb_define_method(rb_cBigDecimal, "precs", BigDecimal_prec, 0); rb_define_method(rb_cBigDecimal, "precision", BigDecimal_precision, 0); + rb_define_method(rb_cBigDecimal, "scale", BigDecimal_scale, 0); rb_define_method(rb_cBigDecimal, "n_significant_digits", BigDecimal_n_significant_digits, 0); rb_define_method(rb_cBigDecimal, "add", BigDecimal_add2, 2); |