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comedi_test: deal with INSN_GTOD values more carefully

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Try and avoid arithmetic overflow when converting the difference between
two INSN_GTOD timestamps to a signed number of microseconds.
This commit is contained in:
Ian Abbott 2016-06-20 11:29:14 +01:00
parent a4dd004076
commit c45f319171
1 changed files with 13 additions and 2 deletions
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15
testing/insn_read_time.c
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@ -19,6 +19,7 @@ int test_insn_read_time(void)
comedi_insnlist il;
lsampl_t t1[2],t2[2];
lsampl_t data;
long diffus;
int save_errno;
int ret;
@ -60,8 +61,18 @@ int test_insn_read_time(void)
printf("W: comedi_do_insn: returned %d (expected 3)\n",ret);
}
printf("read time: %ld us\n",
(long)(t2[0]-t1[0])*1000000+(t2[1]-t1[1]));
if (t2[0] >= t1[0]) {
diffus = (long)(t2[0] - t1[0]);
} else {
diffus = -(long)(t1[0] - t2[0]);
}
diffus *= 1000000;
if (t2[1] >= t1[1]) {
diffus += (long)(t2[1] - t1[1]);
} else {
diffus -= (long)(t1[1] - t2[1]);
}
printf("read time: %ld us\n", diffus);
return 0;