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pcm/Traits: add typedef "sum_type" 

Allow 32 bit platforms to use 32 bit instead of 64 bit for summing 24
bit samples.
This commit is contained in:
Max Kellermann 2013-12-02 11:45:03 +01:00
parent f761d583b5
commit c6ef0e8887
3 changed files with 16 additions and 5 deletions
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8
src/pcm/PcmChannels.cxx
View File

@ -44,8 +44,8 @@ static typename Traits::value_type
StereoToMono(typename Traits::value_type _a,
typename Traits::value_type _b)
{
typename Traits::long_type a(_a);
typename Traits::long_type b(_b);
typename Traits::sum_type a(_a);
typename Traits::sum_type b(_b);
return typename Traits::value_type((a + b) / 2);
}
@ -76,7 +76,7 @@ NToStereo(typename Traits::pointer_type dest,
assert((end - src) % src_channels == 0);
while (src != end) {
typename Traits::long_type sum = *src++;
typename Traits::sum_type sum = *src++;
for (unsigned c = 1; c < src_channels; ++c)
sum += *src++;
@ -101,7 +101,7 @@ NToM(typename Traits::pointer_type dest,
assert((end - src) % src_channels == 0);
while (src != end) {
typename Traits::long_type sum = *src++;
typename Traits::sum_type sum = *src++;
for (unsigned c = 1; c < src_channels; ++c)
sum += *src++;

2
src/pcm/PcmMix.cxx
View File

@ -125,7 +125,7 @@ template<SampleFormat F, class Traits=SampleTraits<F>>
static typename Traits::value_type
PcmAdd(typename Traits::value_type _a, typename Traits::value_type _b)
{
typename Traits::long_type a(_a), b(_b);
typename Traits::sum_type a(_a), b(_b);
return PcmClamp<F, Traits>(a + b);
}

11
src/pcm/Traits.hxx
View File

@ -50,6 +50,13 @@ struct SampleTraits<SampleFormat::S8> {
*/
typedef const value_type *const_pointer_type;
/**
* A "long" type that is large and accurate enough for adding
* two values without risking an (integer) overflow or
* (floating point) precision loss.
*/
typedef int sum_type;
/**
* A "long" type that is large and accurate enough for
* arithmetic without risking an (integer) overflow or
@ -75,6 +82,7 @@ struct SampleTraits<SampleFormat::S16> {
typedef value_type *pointer_type;
typedef const value_type *const_pointer_type;
typedef int_least32_t sum_type;
typedef int_least32_t long_type;
static constexpr size_t SAMPLE_SIZE = sizeof(value_type);
@ -87,6 +95,7 @@ struct SampleTraits<SampleFormat::S32> {
typedef value_type *pointer_type;
typedef const value_type *const_pointer_type;
typedef int_least64_t sum_type;
typedef int_least64_t long_type;
static constexpr size_t SAMPLE_SIZE = sizeof(value_type);
@ -99,6 +108,7 @@ struct SampleTraits<SampleFormat::S24_P32> {
typedef value_type *pointer_type;
typedef const value_type *const_pointer_type;
typedef int_least32_t sum_type;
typedef int_least64_t long_type;
static constexpr size_t SAMPLE_SIZE = sizeof(value_type);
@ -111,6 +121,7 @@ struct SampleTraits<SampleFormat::FLOAT> {
typedef value_type *pointer_type;
typedef const value_type *const_pointer_type;
typedef float sum_type;
typedef float long_type;
static constexpr size_t SAMPLE_SIZE = sizeof(value_type);