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Made final switch to permit high-sampling rate Atari audio.

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This commit is contained in:
Thomas Harte 2017-04-15 21:18:00 -04:00
parent f95015c7f6
commit ed6b135015
2 changed files with 14 additions and 11 deletions
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21
Machines/Atari2600/Speaker.cpp
View File

@ -44,6 +44,7 @@ void Atari2600::Speaker::get_samples(unsigned int number_of_samples, int16_t *ta
target[c] = 0;
for(int channel = 0; channel < 2; channel++) {
divider_counter_[channel] ++;
int divider_value = divider_counter_[channel] / (38 / CPUTicksPerAudioTick);
int level = 0;
switch(control_[channel]) {
case 0x0: case 0xb: // constant 1
@ -51,24 +52,24 @@ void Atari2600::Speaker::get_samples(unsigned int number_of_samples, int16_t *ta
break;
case 0x4: case 0x5: // div2 tone
level = (divider_counter_[channel] / (divider_[channel]+1))&1;
level = (divider_value / (divider_[channel]+1))&1;
break;
case 0xc: case 0xd: // div6 tone
level = (divider_counter_[channel] / ((divider_[channel]+1)*3))&1;
level = (divider_value / ((divider_[channel]+1)*3))&1;
break;
case 0x6: case 0xa: // div31 tone
level = (divider_counter_[channel] / (divider_[channel]+1))%30 <= 18;
level = (divider_value / (divider_[channel]+1))%30 <= 18;
break;
case 0xe: // div93 tone
level = (divider_counter_[channel] / ((divider_[channel]+1)*3))%30 <= 18;
level = (divider_value / ((divider_[channel]+1)*3))%30 <= 18;
break;
case 0x1: // 4-bit poly
level = poly4_counter_[channel]&1;
if(divider_counter_[channel] == divider_[channel]+1) {
if(divider_value == divider_[channel]+1) {
divider_counter_[channel] = 0;
advance_poly4(channel);
}
@ -76,14 +77,14 @@ void Atari2600::Speaker::get_samples(unsigned int number_of_samples, int16_t *ta
case 0x2: // 4-bit poly div31
level = poly4_counter_[channel]&1;
if(divider_counter_[channel]%(30*(divider_[channel]+1)) == 18) {
if(divider_value%(30*(divider_[channel]+1)) == 18) {
advance_poly4(channel);
}
break;
case 0x3: // 5/4-bit poly
level = output_state_[channel];
if(divider_counter_[channel] == divider_[channel]+1) {
if(divider_value == divider_[channel]+1) {
if(poly5_counter_[channel]&1) {
output_state_[channel] = poly4_counter_[channel]&1;
advance_poly4(channel);
@ -94,7 +95,7 @@ void Atari2600::Speaker::get_samples(unsigned int number_of_samples, int16_t *ta
case 0x7: case 0x9: // 5-bit poly
level = poly5_counter_[channel]&1;
if(divider_counter_[channel] == divider_[channel]+1) {
if(divider_value == divider_[channel]+1) {
divider_counter_[channel] = 0;
advance_poly5(channel);
}
@ -102,7 +103,7 @@ void Atari2600::Speaker::get_samples(unsigned int number_of_samples, int16_t *ta
case 0xf: // 5-bit poly div6
level = poly5_counter_[channel]&1;
if(divider_counter_[channel] == (divider_[channel]+1)*3) {
if(divider_value == (divider_[channel]+1)*3) {
divider_counter_[channel] = 0;
advance_poly5(channel);
}
@ -110,7 +111,7 @@ void Atari2600::Speaker::get_samples(unsigned int number_of_samples, int16_t *ta
case 0x8: // 9-bit poly
level = poly9_counter_[channel]&1;
if(divider_counter_[channel] == divider_[channel]+1) {
if(divider_value == divider_[channel]+1) {
divider_counter_[channel] = 0;
advance_poly9(channel);
}

4
Machines/Atari2600/Speaker.hpp
View File

@ -13,7 +13,9 @@
namespace Atari2600 {
const int CPUTicksPerAudioTick = 38;
// This should be a divisor of 38; audio counters are updated every 38 cycles — though lesser dividers
// will give greater resolution to changes in audio state. 1, 2 and 19 are the only divisors of 38.
const int CPUTicksPerAudioTick = 2;
class Speaker: public ::Outputs::Filter<Speaker> {
public: