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analog: Implement division for sr_rational

This commit is contained in:
Stefan Brüns 2016-05-01 01:36:23 +02:00 committed by Uwe Hermann
parent ee1b6054d6
commit 17d5a11c69
3 changed files with 90 additions and 0 deletions
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2
include/libsigrok/proto.h
View File

@ -36,6 +36,8 @@ SR_API void sr_rational_set(struct sr_rational *r, int64_t p, uint64_t q);
SR_API int sr_rational_eq(const struct sr_rational *a, const struct sr_rational *b);
SR_API int sr_rational_mult(struct sr_rational *res, const struct sr_rational *a,
const struct sr_rational *b);
SR_API int sr_rational_div(struct sr_rational *res, const struct sr_rational *num,
const struct sr_rational *div);
/*--- backend.c -------------------------------------------------------------*/

43
src/analog.c
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@ -444,6 +444,8 @@ SR_API int sr_rational_eq(const struct sr_rational *a, const struct sr_rational
* otherwise. If the resulting nominator/denominator are relatively prime,
* this may not be possible.
*
* It is save to use the same variable for result and input values
*
* @retval SR_OK Success.
* @retval SR_ERR_ARG Resulting value to large
*
@ -506,4 +508,45 @@ SR_API int sr_rational_mult(struct sr_rational *res, const struct sr_rational *a
#endif
}
/**
* Divide rational a by rational b
*
* @param[in] num numerator
* @param[in] div divisor
* @param[out] res Result
*
* The resulting nominator/denominator are reduced if the result would not fit
* otherwise. If the resulting nominator/denominator are relatively prime,
* this may not be possible.
*
* It is save to use the same variable for result and input values
*
* @retval SR_OK Success.
* @retval SR_ERR_ARG Division by zero
* @retval SR_ERR_ARG Denominator of divisor to large
* @retval SR_ERR_ARG Resulting value to large
*
* @since 0.5.0
*/
SR_API int sr_rational_div(struct sr_rational *res, const struct sr_rational *num,
const struct sr_rational *div)
{
struct sr_rational t;
if (div->q > INT64_MAX)
return SR_ERR_ARG;
if (div->p == 0)
return SR_ERR_ARG;
if (div->p > 0) {
t.p = div->q;
t.q = div->p;
} else {
t.p = -div->q;
t.q = -div->p;
}
return sr_rational_mult(res, num, &t);
}
/** @} */

45
tests/analog.c
View File

@ -266,6 +266,50 @@ START_TEST(test_mult_rational)
}
END_TEST
START_TEST(test_div_rational)
{
const struct sr_rational r[][3] = {
/* a * b = c */
{ { 1, 1 }, { 1, 1 }, { 1, 1 }},
{ { 2, 1 }, { 1, 3 }, { 6, 1 }},
{ { 1, 2 }, { 1, 2 }, { 1, 1 }},
/* Test negative numbers */
{ { -1, 2 }, { 1, 2 }, { -1, 1 }},
{ { -1, 2 }, { -1, 2 }, { 1, 1 }},
{ { -(1ll<<20), (1ll<<10) }, { -1, (1ll<<20) }, { (1ll<<30), 1 }},
/* Test reduction */
{ { INT32_MAX, (1ll<<12) }, { 1, (1<<2) }, { INT32_MAX, (1ll<<10) }},
{ { INT64_MAX, (1ll<<63) }, { 1, (1<<3) }, { INT64_MAX, (1ll<<60) }},
/* Test large numbers */
{ { (1ll<<40), (1ll<<10) }, { 1, (1ll<<30) }, { (1ll<<60), 1 }},
{ { -(1ll<<40), (1ll<<10) }, { -1, (1ll<<30) }, { (1ll<<60), 1 }},
{ { 10000*3, 4 }, { 1, 80000*3 }, { 200000000*9, 1 }},
{ { 4, 10000*3 }, { 80000*3, 1 }, { 1, 200000000*9 }},
{ { -10000*3, 4 }, { 1, 80000*3 }, { -200000000*9, 1 }},
{ { 10000*3, 4 }, { -1, 80000*3 }, { -200000000*9, 1 }},
};
for (unsigned i = 0; i < ARRAY_SIZE(r); i++) {
struct sr_rational res;
int rc = sr_rational_div(&res, &r[i][0], &r[i][1]);
fail_unless(rc == SR_OK);
fail_unless(sr_rational_eq(&res, &r[i][2]) == 1,
"sr_rational_mult() failed: [%d] %ld/%lu != %ld/%lu.",
i, res.p, res.q, r[i][2].p, r[i][2].q);
}
{
struct sr_rational res;
int rc = sr_rational_div(&res, &r[0][0], &((struct sr_rational){ 0, 5 }));
fail_unless(rc == SR_ERR_ARG);
}
}
END_TEST
Suite *suite_analog(void)
{
Suite *s;
@ -282,6 +326,7 @@ Suite *suite_analog(void)
tcase_add_test(tc, test_set_rational_null);
tcase_add_test(tc, test_cmp_rational);
tcase_add_test(tc, test_mult_rational);
tcase_add_test(tc, test_div_rational);
suite_add_tcase(s, tc);
return s;