bpo-33781: audioop: enhance rounding double as int (GH-7447) (GH-7452)
Move the floor() call into fbound() to call floor() on a double
rather than an int. The change should enhance the rounding.
Document also (int)double rounding mode.
(cherry picked from commit 45e4efba7fa2abe61d25e4f8b5bf482e19ff1280)
diff --git a/Modules/audioop.c b/Modules/audioop.c
index ad7336c..4229038 100644
--- a/Modules/audioop.c
+++ b/Modules/audioop.c
@@ -31,11 +31,18 @@
static int
fbound(double val, double minval, double maxval)
{
- if (val > maxval)
+ if (val > maxval) {
val = maxval;
- else if (val < minval + 1)
+ }
+ else if (val < minval + 1.0) {
val = minval;
- return val;
+ }
+
+ /* Round towards minus infinity (-inf) */
+ val = floor(val);
+
+ /* Cast double to integer: round towards zero */
+ return (int)val;
}
@@ -793,8 +800,8 @@
if ( size == 1 ) val = (int)*CHARP(cp, i);
else if ( size == 2 ) val = (int)*SHORTP(cp, i);
else if ( size == 4 ) val = (int)*LONGP(cp, i);
- fval = (double)val*factor;
- val = (int)floor(fbound(fval, minval, maxval));
+ fval = (double)val * factor;
+ val = fbound(fval, minval, maxval);
if ( size == 1 ) *CHARP(ncp, i) = (signed char)val;
else if ( size == 2 ) *SHORTP(ncp, i) = (short)val;
else if ( size == 4 ) *LONGP(ncp, i) = (Py_Int32)val;
@@ -837,8 +844,8 @@
if ( size == 1 ) val2 = (int)*CHARP(cp, i+1);
else if ( size == 2 ) val2 = (int)*SHORTP(cp, i+2);
else if ( size == 4 ) val2 = (int)*LONGP(cp, i+4);
- fval = (double)val1*fac1 + (double)val2*fac2;
- val1 = (int)floor(fbound(fval, minval, maxval));
+ fval = (double)val1 * fac1 + (double)val2 * fac2;
+ val1 = fbound(fval, minval, maxval);
if ( size == 1 ) *CHARP(ncp, i/2) = (signed char)val1;
else if ( size == 2 ) *SHORTP(ncp, i/2) = (short)val1;
else if ( size == 4 ) *LONGP(ncp, i/2)= (Py_Int32)val1;
@@ -881,11 +888,11 @@
else if ( size == 2 ) val = (int)*SHORTP(cp, i);
else if ( size == 4 ) val = (int)*LONGP(cp, i);
- fval = (double)val*fac1;
- val1 = (int)floor(fbound(fval, minval, maxval));
+ fval = (double)val * fac1;
+ val1 = fbound(fval, minval, maxval);
- fval = (double)val*fac2;
- val2 = (int)floor(fbound(fval, minval, maxval));
+ fval = (double)val * fac2;
+ val2 = fbound(fval, minval, maxval);
if ( size == 1 ) *CHARP(ncp, i*2) = (signed char)val1;
else if ( size == 2 ) *SHORTP(ncp, i*2) = (short)val1;
@@ -944,7 +951,7 @@
else {
double fval = (double)val1 + (double)val2;
/* truncate in case of overflow */
- newval = (int)floor(fbound(fval, minval, maxval));
+ newval = fbound(fval, minval, maxval);
}
if ( size == 1 ) *CHARP(ncp, i) = (signed char)newval;