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SCUMM: Optimize player_appleII sample buffer

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The AppleII sound player works in two phases: writing samples to the
sample buffer (sample
generation) or reading samples from the buffer and passing it to ScummVM's
output callback.
The sample buffer is read completely in the reading phase so the entries
of the already read samples of the buffer can be reused again during the
next write phase.
This commit is contained in:
Tobias Gunkel 2011-12-21 10:10:42 +01:00
parent 3a9f2c5f5b
commit f7a869ccc5
1 changed files with 53 additions and 37 deletions
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90
engines/scumm/player_appleII.h
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@ -35,13 +35,20 @@ namespace Scumm {
class ScummEngine;
class DynamicMemoryStream {
/*
* Optimized for use with periodical read/write phases when the buffer
* is filled in a write phase and completely read in a read phase.
* The growing strategy is optimized for repeated small (e.g. 2 bytes)
* single writes resulting in large buffers
* (avg.: 4KB, max: 18KB @ 16bit/22.050kHz (MM sound21)).
*/
class SampleBuffer {
public:
DynamicMemoryStream() : _data(0) {
SampleBuffer() : _data(0) {
clear();
}
~DynamicMemoryStream() {
~SampleBuffer() {
free(_data);
}
@ -49,50 +56,61 @@ public:
free(_data);
_data = 0;
_capacity = 0;
_size = 0;
_ptr = 0;
_pos = 0;
_writePos = 0;
_readPos = 0;
}
void ensureCapacity(uint32 new_len) {
if (new_len <= _capacity)
return;
byte *old_data = _data;
_capacity *= 2;
if (_capacity < new_len + 2048)
_capacity = new_len + 2048;
_data = (byte *)malloc(_capacity);
_ptr = _data + _pos;
if (old_data) {
// Copy old data
memcpy(_data, old_data, _size);
free(old_data);
void ensureFree(uint32 needed) {
// if data was read completely, reset read/write pos to front
if ((_writePos != 0) && (_writePos == _readPos)) {
_writePos = 0;
_readPos = 0;
}
_size = new_len;
// check for enough space at end of buffer
uint32 freeEndCnt = _capacity - _writePos;
if (needed <= freeEndCnt)
return;
uint32 avail = availableSize();
// check for enough space at beginning and end of buffer
if (needed <= _readPos + freeEndCnt) {
// move unread data to front of buffer
memmove(_data, _data + _readPos, avail);
_writePos = avail;
_readPos = 0;
} else { // needs a grow
byte *old_data = _data;
uint32 new_len = avail + needed;
_capacity = new_len + 2048;
_data = (byte *)malloc(_capacity);
if (old_data) {
// copy old unread data to front of new buffer
memcpy(_data, old_data + _readPos, avail);
free(old_data);
_writePos = avail;
_readPos = 0;
}
}
}
uint32 availableSize() const {
if (_readPos >= _size)
if (_readPos >= _writePos)
return 0;
return _size - _readPos;
return _writePos - _readPos;
}
virtual uint32 write(const void *dataPtr, uint32 dataSize) {
ensureCapacity(_pos + dataSize);
memcpy(_ptr, dataPtr, dataSize);
_ptr += dataSize;
_pos += dataSize;
if (_pos > _size)
_size = _pos;
ensureFree(dataSize);
memcpy(_data + _writePos, dataPtr, dataSize);
_writePos += dataSize;
return dataSize;
}
uint32 read(byte *dataPtr, uint32 dataSize) const {
uint32 read(byte *dataPtr, uint32 dataSize) {
uint32 avail = availableSize();
if (avail == 0)
return 0;
@ -104,12 +122,10 @@ public:
}
private:
mutable uint32 _readPos;
uint32 _writePos;
uint32 _readPos;
uint32 _capacity;
uint32 _size;
byte *_ptr;
byte *_data;
uint32 _pos;
};
// CPU_CLOCK according to AppleWin
@ -214,7 +230,7 @@ private:
int _sampleCyclesSumFP; /* (fixed precision) */
int _volume; /* 0 - 256 */
static const int _maxVolume = 256;
DynamicMemoryStream _buffer;
SampleBuffer _buffer;
};
class AppleII_SoundFunction;