Fix PCM playback in ZSM backend

backends/playback/zsm/x16emu/vera_pcm.c

@@ -180,14 +180,21 @@ pcm_render(int16_t *buf, unsigned num_samples)
 		*(buf++) = (int16_t)((int32_t)cur_r * volume_lut[ctrl & 0xF] / 64);
 	}
 }
-uint32_t pcm_fifo_avail(void) {
+uint32_t pcm_fifo_cnt(void) {
-	uint32_t cnt_adj = fifo_cnt;
+	return fifo_cnt;
+}
+uint32_t pcm_sample_size(void) {
+	uint32_t output = 1;
 	switch ((ctrl >> 4) & 3) {
-		case 3: cnt_adj /= 2;
+		case 3: output *= 2;
 		case 2:
-		case 1: cnt_adj /= 2;
+		case 1: output *= 2;
 		case 0: break;
 	}
+	return output;
+}
+uint32_t pcm_fifo_avail(void) {
+	uint32_t cnt_adj = fifo_cnt / pcm_sample_size();
 	uint32_t output = 0;
 	uint32_t _phase = phase;
 	while (cnt_adj != 0) {

backends/playback/zsm/x16emu/vera_pcm.h

@@ -16,3 +16,5 @@ void     pcm_write_fifo(uint8_t val);
 void     pcm_render(int16_t *buf, unsigned num_samples);
 uint32_t pcm_fifo_avail(void);
 bool     pcm_is_fifo_almost_empty(void);
+uint32_t pcm_fifo_cnt(void);
+uint32_t pcm_sample_size(void);

backends/playback/zsm/zsm_backend.cpp

@@ -47,6 +47,37 @@ void ZsmBackend::load(const char *filename) {
     file->read(loop_point, 1, 1);
     pcm_offset++;
     pcm_data_offs = ((((uint16_t)loop_point[0]) + 1) * 16) + pcm_offset;
+    for (uint8_t i = 0; i <= loop_point[0]; i++) {
+	    uint16_t instdef = (i * 16) + 1;
+		pcm_instrument *inst = new pcm_instrument();
+	    file->seek(pcm_offset + instdef, SeekType::SET);
+	    file->read(&inst->geom, 1, 1);
+	    uint8_t bytes[10];
+	    file->read(bytes, 10, 1);
+	    inst->loop_rem = bytes[9];
+	    inst->loop_rem <<= 8;
+	    inst->loop_rem |= bytes[8];
+	    inst->loop_rem <<= 8;
+	    inst->loop_rem |= bytes[7];
+	    inst->loop = loop_rem;
+	    inst->islooped = bytes[6] & 0x80;
+	    inst->remain = bytes[5];
+	    inst->remain <<= 8;
+	    inst->remain |= bytes[4];
+	    inst->remain <<= 8;
+	    inst->remain |= bytes[3];
+	    uint32_t cur = bytes[2];
+	    cur <<= 8;
+	    cur |= bytes[1];
+	    cur <<= 8;
+	    cur |= bytes[0];
+	    cur += pcm_data_offs;
+	    inst->data = (uint8_t*)malloc(inst->remain);
+	    file->seek(cur, SeekType::SET);
+	    file->read(inst->data, 1, inst->remain);
+	    inst->loop_rem = inst->remain - inst->loop_rem;
+		instruments.push_back(inst);
+    }
     file->seek(music_data_start, SeekType::SET);
     this->loop_point = std::max(this->loop_point, (uint32_t)music_data_start);
     double prev_time = 0.0;
@@ -106,6 +137,11 @@ void ZsmBackend::cleanup() {
     audio_buf.clear();
     SDL_FreeAudioStream(fm_stream);
     fm_stream = nullptr;
+    audio_sample = nullptr;
+    for (auto inst : instruments) {
+    	delete inst;
+    }
+    instruments.clear();
 }
 void ZsmBackend::tick(bool step) {
     delayTicks -= 1;
@@ -167,40 +203,18 @@ void ZsmBackend::tick(bool step) {
                                     uint8_t ctrl = pcm_read_ctrl();
                                     pcm_write_ctrl(ctrl | 0x80);
                                     uint16_t pcm_idx = cmd.extcmd.pcm[i + 1];
-                                    uint16_t instdef = pcm_idx * 16;
+                                    pcm_instrument *inst = instruments[pcm_idx];
-                                    file->seek(pcm_offset + instdef, SeekType::SET);
-                                    uint8_t geom;
-                                    file->read(&geom, 1, 1);
                                     ctrl = pcm_read_ctrl() & 0x0F;
-                                    ctrl |= geom & 0x30;
+                                    ctrl |= inst->geom & 0x30;
                                     pcm_write_ctrl(ctrl);
-                                    uint8_t bytes[10];
+                                    audio_sample = inst->data;
-                                    file->read(bytes, 10, 1);
+                                    loop = inst->loop;
-                                    loop_rem = bytes[9];
+                                    loop_rem = inst->loop_rem;
-                                    loop_rem <<= 8;
+                                    remain = inst->remain;
-                                    loop_rem |= bytes[8];
+                                    islooped = inst->islooped;
-                                    loop_rem <<= 8;
+                                    cur = 0;
-                                    loop_rem |= bytes[7];
-                                    loop = loop_rem;
-                                    islooped = bytes[6] & 0x80;
-                                    remain = bytes[5];
-                                    remain <<= 8;
-                                    remain |= bytes[4];
-                                    remain <<= 8;
-                                    remain |= bytes[3];
-                                    cur = bytes[2];
-                                    cur <<= 8;
-                                    cur |= bytes[1];
-                                    cur <<= 8;
-                                    cur |= bytes[0];
-                                    cur += pcm_data_offs;
-                                    loop += cur;
-                                    loop_rem = remain - loop_rem;
-                                    file->seek(file_pos, SeekType::SET);
                                 } break;
                             }
-                            //cmd.extcmd.pcm
-                            audio_step(0);
                         } break;
                     }
                 // Nothing handled yet.

backends/playback/zsm/zsm_backend.hpp

@@ -60,6 +60,17 @@ struct ZsmCommand {
     };
     ~ZsmCommand();
 };
+struct pcm_instrument {
+	uint8_t geom;
+	uint32_t loop_rem;
+	uint32_t loop;
+	bool islooped;
+	uint32_t remain;
+	uint8_t *data = nullptr;
+	inline ~pcm_instrument() {
+		if (data != nullptr) free((void*)data);
+	}
+};
 class ZsmBackend : public PlaybackBackend {
     File *file;
     Fifo<int16_t> audio_buf;
@@ -80,6 +91,8 @@ class ZsmBackend : public PlaybackBackend {
     uint32_t pcm_loop_point;
     uint32_t rem_point;
     SDL_AudioStream *fm_stream;
+    std::vector<pcm_instrument*> instruments;
+    uint8_t *audio_sample = nullptr;
     int16_t combine_audio(int16_t a, int16_t b) {
         return (int16_t)((((int32_t)a) + ((int32_t)b)) >> 1);
     }
@@ -96,11 +109,8 @@ class ZsmBackend : public PlaybackBackend {
                 }
             }
             size_t oldpos = file->get_pos();
-            file->seek((cur++), SeekType::SET);
+            uint8_t sample = audio_sample[cur++];
-            uint8_t sample;
-            file->read(&sample, 1, 1);
             pcm_write_fifo(sample);
-            file->seek(oldpos, SeekType::SET);
         }
         samples *= 2;
     	int16_t *psg_ptr = psg_buf.get_item_sized<int16_t>(samples);