From b0e5fa652b81a09c4c960998450952f921f41474 Mon Sep 17 00:00:00 2001
From: Serge Petrenko <sergepetrenko@tarantool.org>
Date: Tue, 16 Jul 2019 19:30:10 +0300
Subject: [PATCH] decimal: fix decimal.round() when scale == 0
Fixes decimal.round() with zero scale, fixes an error with
decimal.round() when rounding leads to a number with the same
precision, for example, decimal.round(9.9, 0) -> 10.
Follow-up #692
---
src/lib/core/decimal.c | 8 ++++----
test/app/decimal.result | 18 ++++++++++++++++++
test/app/decimal.test.lua | 6 ++++++
3 files changed, 28 insertions(+), 4 deletions(-)
diff --git a/src/lib/core/decimal.c b/src/lib/core/decimal.c
index 634dd61b0c..6ef351f814 100644
--- a/src/lib/core/decimal.c
+++ b/src/lib/core/decimal.c
@@ -172,14 +172,14 @@ decimal_round(decimal_t *dec, int scale)
if (scale < 0 || scale > DECIMAL_MAX_DIGITS)
return NULL;
- if (scale > decimal_scale(dec))
+ if (scale >= decimal_scale(dec))
return dec;
- int ndig = decimal_precision(dec) - decimal_scale(dec) + scale;
+ int ndig = MAX(decimal_precision(dec) - decimal_scale(dec) + scale, 1);
decContext context = {
ndig, /* Precision */
- ndig - 1, /* emax */
- -1, /* emin */
+ ndig, /* emax */
+ scale != 0 ? -1 : 0, /* emin */
DECIMAL_ROUNDING, /* rounding */
0, /* no traps */
0, /* zero status */
diff --git a/test/app/decimal.result b/test/app/decimal.result
index 9185e24cc2..b53f4e75da 100644
--- a/test/app/decimal.result
+++ b/test/app/decimal.result
@@ -510,3 +510,21 @@ decimal.trim(a)
| ---
| - '123.456789'
| ...
+
+-- check correct rounding when scale = 0
+decimal.round(decimal.new(0.9), 0)
+ | ---
+ | - '1'
+ | ...
+decimal.round(decimal.new(9.9), 0)
+ | ---
+ | - '10'
+ | ...
+decimal.round(decimal.new(99.9), 0)
+ | ---
+ | - '100'
+ | ...
+decimal.round(decimal.new(99.4), 0)
+ | ---
+ | - '99'
+ | ...
diff --git a/test/app/decimal.test.lua b/test/app/decimal.test.lua
index 43229b2275..cee56d5e70 100644
--- a/test/app/decimal.test.lua
+++ b/test/app/decimal.test.lua
@@ -143,3 +143,9 @@ decimal.trim(decimal.rescale(a, 10))
a = decimal.new('123.456789000000000')
a
decimal.trim(a)
+
+-- check correct rounding when scale = 0
+decimal.round(decimal.new(0.9), 0)
+decimal.round(decimal.new(9.9), 0)
+decimal.round(decimal.new(99.9), 0)
+decimal.round(decimal.new(99.4), 0)
--
GitLab