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Message-ID: <tencent_600EF14B398E2D22167034EA@qq.com>
Date: Tue, 14 Oct 2014 10:17:34 +0800
From: "bobodog" <8192542@...com>
To: "musl" <musl@...ts.openwall.com>
Subject: [math] The math library have some bug for ceil,floor,round functioin, in arm mode
HI,ALL
We use musl in arm process, but found some bugs about math library, x86 process is ok!
Here the test result:
1) In ARM mode: (the result is wrong)
[ 9.235921][kernel/command/cmd-test.c:44] ceil(-0.125000) = 0.000000, floor(-0.125000) = -1.000000, round(-0.125000) = 0.000000
[ 9.238523][kernel/command/cmd-test.c:44] ceil(-0.250000) = 0.000000, floor(-0.250000) = -1.000000, round(-0.250000) = 0.000000
[ 9.239770][kernel/command/cmd-test.c:44] ceil(-0.375000) = 0.000000, floor(-0.375000) = -1.000000, round(-0.375000) = 0.000000
[ 9.241081][kernel/command/cmd-test.c:44] ceil(-0.500000) = 0.000000, floor(-0.500000) = -1.000000, round(-0.500000) = -0.500000
[ 9.242361][kernel/command/cmd-test.c:44] ceil(-0.625000) = 0.000000, floor(-0.625000) = -1.000000, round(-0.625000) = -0.625000
[ 9.243637][kernel/command/cmd-test.c:44] ceil(-0.750000) = 0.000000, floor(-0.750000) = -1.000000, round(-0.750000) = -0.750000
[ 9.244879][kernel/command/cmd-test.c:44] ceil(-0.875000) = 0.000000, floor(-0.875000) = -1.000000, round(-0.875000) = -0.875000
[ 9.246183][kernel/command/cmd-test.c:44] ceil(-1.000000) = -1.000000, floor(-1.000000) = -1.000000, round(-1.000000) = -1.000000
[ 9.247457][kernel/command/cmd-test.c:44] ceil(-1.125000) = -1.125000, floor(-1.125000) = -1.125000, round(-1.125000) = -1.125000
[ 9.248333][kernel/command/cmd-test.c:44] ceil(-1.250000) = -1.250000, floor(-1.250000) = -1.250000, round(-1.250000) = -1.250000
[ 9.249303][kernel/command/cmd-test.c:44] ceil(-1.375000) = -1.375000, floor(-1.375000) = -1.375000, round(-1.375000) = -1.375000
[ 9.250456][kernel/command/cmd-test.c:44] ceil(-1.500000) = -1.500000, floor(-1.500000) = -1.500000, round(-1.500000) = -1.500000
[ 9.251730][kernel/command/cmd-test.c:44] ceil(-1.625000) = -1.625000, floor(-1.625000) = -1.625000, round(-1.625000) = -1.625000
[ 9.252975][kernel/command/cmd-test.c:44] ceil(-1.750000) = -1.750000, floor(-1.750000) = -1.750000, round(-1.750000) = -1.750000
[ 9.254272][kernel/command/cmd-test.c:44] ceil(-1.875000) = -1.875000, floor(-1.875000) = -1.875000, round(-1.875000) = -1.875000
[ 9.255563][kernel/command/cmd-test.c:44] ceil(-2.000000) = -2.000000, floor(-2.000000) = -2.000000, round(-2.000000) = -2.000000
[ 9.256813][kernel/command/cmd-test.c:44] ceil(-2.125000) = -2.125000, floor(-2.125000) = -2.125000, round(-2.125000) = -2.125000
[ 9.257610][kernel/command/cmd-test.c:44] ceil(-2.250000) = -2.250000, floor(-2.250000) = -2.250000, round(-2.250000) = -2.250000
[ 9.258029][kernel/command/cmd-test.c:44] ceil(-2.375000) = -2.375000, floor(-2.375000) = -2.375000, round(-2.375000) = -2.375000
[ 9.259500][kernel/command/cmd-test.c:44] ceil(-2.500000) = -2.500000, floor(-2.500000) = -2.500000, round(-2.500000) = -2.500000
2) In X86 mode: (the result is correct)
[ 3.790000][kernel/command/cmd-test.c:44] ceil(-0.125000) = 0.000000, floor(-0.125000) = -1.000000, round(-0.125000) = 0.000000
[ 3.790000][kernel/command/cmd-test.c:44] ceil(-0.250000) = 0.000000, floor(-0.250000) = -1.000000, round(-0.250000) = 0.000000
[ 3.790000][kernel/command/cmd-test.c:44] ceil(-0.375000) = 0.000000, floor(-0.375000) = -1.000000, round(-0.375000) = 0.000000
[ 3.790000][kernel/command/cmd-test.c:44] ceil(-0.500000) = 0.000000, floor(-0.500000) = -1.000000, round(-0.500000) = -1.000000
[ 3.790000][kernel/command/cmd-test.c:44] ceil(-0.625000) = 0.000000, floor(-0.625000) = -1.000000, round(-0.625000) = -1.000000
[ 3.790000][kernel/command/cmd-test.c:44] ceil(-0.750000) = 0.000000, floor(-0.750000) = -1.000000, round(-0.750000) = -1.000000
[ 3.790000][kernel/command/cmd-test.c:44] ceil(-0.875000) = 0.000000, floor(-0.875000) = -1.000000, round(-0.875000) = -1.000000
[ 3.790000][kernel/command/cmd-test.c:44] ceil(-1.000000) = -1.000000, floor(-1.000000) = -1.000000, round(-1.000000) = -1.000000
[ 3.790000][kernel/command/cmd-test.c:44] ceil(-1.125000) = -1.000000, floor(-1.125000) = -2.000000, round(-1.125000) = -1.000000
[ 3.790000][kernel/command/cmd-test.c:44] ceil(-1.250000) = -1.000000, floor(-1.250000) = -2.000000, round(-1.250000) = -1.000000
[ 3.790000][kernel/command/cmd-test.c:44] ceil(-1.375000) = -1.000000, floor(-1.375000) = -2.000000, round(-1.375000) = -1.000000
[ 3.790000][kernel/command/cmd-test.c:44] ceil(-1.500000) = -1.000000, floor(-1.500000) = -2.000000, round(-1.500000) = -2.000000
[ 3.790000][kernel/command/cmd-test.c:44] ceil(-1.625000) = -1.000000, floor(-1.625000) = -2.000000, round(-1.625000) = -2.000000
[ 3.790000][kernel/command/cmd-test.c:44] ceil(-1.750000) = -1.000000, floor(-1.750000) = -2.000000, round(-1.750000) = -2.000000
[ 3.790000][kernel/command/cmd-test.c:44] ceil(-1.875000) = -1.000000, floor(-1.875000) = -2.000000, round(-1.875000) = -2.000000
[ 3.790000][kernel/command/cmd-test.c:44] ceil(-2.000000) = -2.000000, floor(-2.000000) = -2.000000, round(-2.000000) = -2.000000
[ 3.790000][kernel/command/cmd-test.c:44] ceil(-2.125000) = -2.000000, floor(-2.125000) = -3.000000, round(-2.125000) = -2.000000
[ 3.790000][kernel/command/cmd-test.c:44] ceil(-2.250000) = -2.000000, floor(-2.250000) = -3.000000, round(-2.250000) = -2.000000
[ 3.790000][kernel/command/cmd-test.c:44] ceil(-2.375000) = -2.000000, floor(-2.375000) = -3.000000, round(-2.375000) = -2.000000
[ 3.790000][kernel/command/cmd-test.c:44] ceil(-2.500000) = -2.000000, floor(-2.500000) = -3.000000, round(-2.500000) = -3.000000
The test code:
int test(int argc, char ** argv)
{
double n = 0.0;
int i;
for(i = 0; i < 20; i++)
{
n = n - 0.125;
printf("ceil(%f) = %f, floor(%f) = %f, round(%f) = %f\n", n, ceil(n), n, floor(n), n, round(n));
}
return 0;
}
May be rint trunc have same problem. this is supper big bug!!!
------------------
____________________________
蒋建军
深圳市九鼎创展科技有限公司
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