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mpd_qpowmod(): calculate result with zero-exponent for compatibility with 

decimal.py. The hack to remove the ideal exponent is no longer required.
This commit is contained in:
Stefan Krah 2012-08-23 15:05:29 +02:00
parent bbd3437c27
commit f21587e3a8
2 changed files with 18 additions and 24 deletions
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8
Modules/_decimal/_decimal.c
View File

@ -3872,10 +3872,6 @@ nm_mpd_qpow(PyObject *base, PyObject *exp, PyObject *mod)
else { else {
mpd_qpowmod(MPD(result), MPD(a), MPD(b), MPD(c), mpd_qpowmod(MPD(result), MPD(a), MPD(b), MPD(c),
CTX(context), &status); CTX(context), &status);
status = (status == MPD_Clamped) ? 0 : status;
/* remove ideal exponent for compatibility with decimal.py */
mpd_qquantize(MPD(result), MPD(result), &zero,
CTX(context), &status);
Py_DECREF(c); Py_DECREF(c);
} }
Py_DECREF(a); Py_DECREF(a);
@ -4905,10 +4901,6 @@ ctx_mpd_qpow(PyObject *context, PyObject *args, PyObject *kwds)
else { else {
mpd_qpowmod(MPD(result), MPD(a), MPD(b), MPD(c), mpd_qpowmod(MPD(result), MPD(a), MPD(b), MPD(c),
CTX(context), &status); CTX(context), &status);
status = (status == MPD_Clamped) ? 0 : status;
/* remove ideal exponent for compatibility with decimal.py */
mpd_qquantize(MPD(result), MPD(result), &zero,
CTX(context), &status);
Py_DECREF(c); Py_DECREF(c);
} }
Py_DECREF(a); Py_DECREF(a);

34
Modules/_decimal/libmpdec/mpdecimal.c
View File

@ -6372,7 +6372,7 @@ mpd_qpow(mpd_t *result, const mpd_t *base, const mpd_t *exp,
*/ */
static inline void static inline void
_mpd_qpowmod_uint(mpd_t *result, mpd_t *base, mpd_uint_t exp, _mpd_qpowmod_uint(mpd_t *result, mpd_t *base, mpd_uint_t exp,
mpd_t *mod, uint32_t *status) const mpd_t *mod, uint32_t *status)
{ {
mpd_context_t maxcontext; mpd_context_t maxcontext;
@ -6383,10 +6383,10 @@ _mpd_qpowmod_uint(mpd_t *result, mpd_t *base, mpd_uint_t exp,
while (exp > 0) { while (exp > 0) {
if (exp & 1) { if (exp & 1) {
mpd_qmul(result, result, base, &maxcontext, status); _mpd_qmul_exact(result, result, base, &maxcontext, status);
mpd_qrem(result, result, mod, &maxcontext, status); mpd_qrem(result, result, mod, &maxcontext, status);
} }
mpd_qmul(base, base, base, &maxcontext, status); _mpd_qmul_exact(base, base, base, &maxcontext, status);
mpd_qrem(base, base, mod, &maxcontext, status); mpd_qrem(base, base, mod, &maxcontext, status);
exp >>= 1; exp >>= 1;
} }
@ -6452,27 +6452,30 @@ mpd_qpowmod(mpd_t *result, const mpd_t *base, const mpd_t *exp,
return; return;
} }
if (!mpd_qcopy(&tmod, mod, status)) {
goto mpd_errors;
}
mpd_set_positive(&tmod);
mpd_maxcontext(&maxcontext); mpd_maxcontext(&maxcontext);
mpd_qround_to_int(&tbase, base, &maxcontext, status); mpd_qrescale(&tmod, mod, 0, &maxcontext, &maxcontext.status);
mpd_qround_to_int(&texp, exp, &maxcontext, status); if (maxcontext.status&MPD_Errors) {
mpd_qround_to_int(&tmod, &tmod, &maxcontext, status); mpd_seterror(result, maxcontext.status&MPD_Errors, status);
goto out;
}
maxcontext.status = 0;
mpd_set_positive(&tmod);
mpd_qround_to_int(&tbase, base, &maxcontext, status);
mpd_set_positive(&tbase);
tbase_exp = tbase.exp; tbase_exp = tbase.exp;
tbase.exp = 0; tbase.exp = 0;
mpd_qround_to_int(&texp, exp, &maxcontext, status);
texp_exp = texp.exp; texp_exp = texp.exp;
texp.exp = 0; texp.exp = 0;
/* base = (base.int % modulo * pow(10, base.exp, modulo)) % modulo */ /* base = (base.int % modulo * pow(10, base.exp, modulo)) % modulo */
mpd_qrem(&tbase, &tbase, &tmod, &maxcontext, status); mpd_qrem(&tbase, &tbase, &tmod, &maxcontext, status);
_settriple(result, MPD_POS, 1, tbase_exp); mpd_qshiftl(result, &one, tbase_exp, status);
mpd_qrem(result, result, &tmod, &maxcontext, status); mpd_qrem(result, result, &tmod, &maxcontext, status);
mpd_qmul(&tbase, &tbase, result, &maxcontext, status); _mpd_qmul_exact(&tbase, &tbase, result, &maxcontext, status);
mpd_qrem(&tbase, &tbase, &tmod, &maxcontext, status); mpd_qrem(&tbase, &tbase, &tmod, &maxcontext, status);
if (mpd_isspecial(&tbase) || if (mpd_isspecial(&tbase) ||
mpd_isspecial(&texp) || mpd_isspecial(&texp) ||
@ -6494,10 +6497,10 @@ mpd_qpowmod(mpd_t *result, const mpd_t *base, const mpd_t *exp,
mpd_qcopy(result, &one, status); mpd_qcopy(result, &one, status);
while (mpd_isfinite(&texp) && !mpd_iszero(&texp)) { while (mpd_isfinite(&texp) && !mpd_iszero(&texp)) {
if (mpd_isodd(&texp)) { if (mpd_isodd(&texp)) {
mpd_qmul(result, result, &tbase, &maxcontext, status); _mpd_qmul_exact(result, result, &tbase, &maxcontext, status);
mpd_qrem(result, result, &tmod, &maxcontext, status); mpd_qrem(result, result, &tmod, &maxcontext, status);
} }
mpd_qmul(&tbase, &tbase, &tbase, &maxcontext, status); _mpd_qmul_exact(&tbase, &tbase, &tbase, &maxcontext, status);
mpd_qrem(&tbase, &tbase, &tmod, &maxcontext, status); mpd_qrem(&tbase, &tbase, &tmod, &maxcontext, status);
mpd_qdivint(&texp, &texp, &two, &maxcontext, status); mpd_qdivint(&texp, &texp, &two, &maxcontext, status);
} }
@ -6515,7 +6518,6 @@ out:
mpd_del(&texp); mpd_del(&texp);
mpd_del(&tmod); mpd_del(&tmod);
mpd_del(&tmp); mpd_del(&tmp);
mpd_qfinalize(result, ctx, status);
return; return;
mpd_errors: mpd_errors: