tree 3b01429207608d6c85da4bed2c7c75fab4f1367f
parent b7560b95994901ae625c0f739499ae59d895c588
author Ryan C. Gordon <icculus@icculus.org> 1526360651 -0400
committer Ryan C. Gordon <icculus@icculus.org> 1526360651 -0400

audio: converting int32 to/from float shouldn't use doubles.

The concern is that a massive int sample, like 0x7FFFFFFF, won't fit in a
float32, which doesn't have enough bits to hold a whole number this large,
just to divide it to get a value between 0 and 1.
Previously we would convert to double, to get more bits, do the division, and
cast back to a float, but this is expensive.

Casting to double is more accurate, but it's 2x to 3x slower. Shifting out
the least significant byte of an int32, so it'll definitely fit in a float,
and dividing by 0x7FFFFF is still accurate to about 5 decimal places, and the
difference doesn't appear to be perceptable.

--HG--
extra : rebase_source : 5be8fca9a33034555682eb22945744cc34cabf71
extra : histedit_source : 2b3c771dcb080326e24fdac1c8f19e5b44ef21b3