From 16be4100808e09a94e802adb58bc1c79e5eefd65 Mon Sep 17 00:00:00 2001
From: Takamichi Horikawa <takamichiho@gmail.com>
Date: Tue, 14 Mar 2017 19:07:57 +0900
Subject: libopna: enable register read

---
 libopna/opna.c      |  5 +++++
 libopna/opna.h      |  1 +
 libopna/opnassg.c   | 13 ++++++++++---
 libopna/opnassg.h   |  2 +-
 libopna/opnatimer.c | 36 ++++++++++++++++++++++++++++++++++--
 libopna/opnatimer.h |  3 +++
 6 files changed, 54 insertions(+), 6 deletions(-)

diff --git a/libopna/opna.c b/libopna/opna.c
index fb9e24a..10155d0 100644
--- a/libopna/opna.c
+++ b/libopna/opna.c
@@ -17,6 +17,11 @@ void opna_writereg(struct opna *opna, unsigned reg, unsigned val) {
   opna_adpcm_writereg(&opna->adpcm, reg, val);
 }
 
+unsigned opna_readreg(const struct opna *opna, unsigned reg) {
+  if (reg > 0xfu) return 0xff;
+  return opna_ssg_readreg(&opna->ssg, reg);
+}
+
 void opna_mix(struct opna *opna, int16_t *buf, unsigned samples) {
   opna_fm_mix(&opna->fm, buf, samples);
   opna_ssg_mix_55466(&opna->ssg, &opna->resampler, buf, samples);
diff --git a/libopna/opna.h b/libopna/opna.h
index b5e9d87..7d7d722 100644
--- a/libopna/opna.h
+++ b/libopna/opna.h
@@ -41,6 +41,7 @@ struct opna {
 
 void opna_reset(struct opna *opna);
 void opna_writereg(struct opna *opna, unsigned reg, unsigned val);
+unsigned opna_readreg(const struct opna *opna, unsigned reg);
 void opna_mix(struct opna *opna, int16_t *buf, unsigned samples);
 unsigned opna_get_mask(const struct opna *opna);
 void opna_set_mask(struct opna *opna, unsigned mask);
diff --git a/libopna/opnassg.c b/libopna/opnassg.c
index 1345502..3c5b108 100644
--- a/libopna/opnassg.c
+++ b/libopna/opnassg.c
@@ -103,6 +103,11 @@ void opna_ssg_writereg(struct opna_ssg *ssg, unsigned reg, unsigned val) {
   }
 }
 
+unsigned opna_ssg_readreg(const struct opna_ssg *ssg, unsigned reg) {
+  if (reg > 0xfu) return 0xff;
+  return ssg->regs[reg];
+}
+
 static int opna_ssg_tone_period(const struct opna_ssg *ssg, int chan) {
   return ssg->regs[0+chan*2] | ((ssg->regs[1+chan*2] & 0xf) << 8);
 }
@@ -173,7 +178,9 @@ void opna_ssg_generate_raw(struct opna_ssg *ssg, int16_t *buf, int samples) {
         ssg->ch[ch].out = !ssg->ch[ch].out;
       }
       if (ssg->mask & (1<<ch)) continue;
-#if 0
+#if 1
+      // may output DC offset
+      // YMF288 seems to disable output when 0 <= Tp < 8
       if (opna_ssg_tone_out(ssg, ch)) {
         int level = opna_ssg_chan_env(ssg, ch)
           ? opna_ssg_env_level(ssg)
@@ -183,12 +190,12 @@ void opna_ssg_generate_raw(struct opna_ssg *ssg, int16_t *buf, int samples) {
 #else
       if (!opna_ssg_tone_silent(ssg, ch)) {
         int level = opna_ssg_channel_level(ssg, ch);
-        out += opna_ssg_tone_out(ssg, ch) ? voltable[level] : -voltable[level];
+        out += (opna_ssg_tone_out(ssg, ch) ? voltable[level] : -voltable[level]) / 2;
       }
 #endif
       
     }
-    buf[i] = out / 4;
+    buf[i] = out / 2;
   }
 }
 
diff --git a/libopna/opnassg.h b/libopna/opnassg.h
index adcd231..1bd607a 100644
--- a/libopna/opnassg.h
+++ b/libopna/opnassg.h
@@ -50,7 +50,7 @@ void opna_ssg_mix_55466(
   struct opna_ssg *ssg, struct opna_ssg_resampler *resampler,
   int16_t *buf, int samples);
 void opna_ssg_writereg(struct opna_ssg *ssg, unsigned reg, unsigned val);
-
+unsigned opna_ssg_readreg(const struct opna_ssg *ssg, unsigned reg);
 // channel level (0 - 31)
 int opna_ssg_channel_level(const struct opna_ssg *ssg, int ch);
 
diff --git a/libopna/opnatimer.c b/libopna/opnatimer.c
index 195e426..789c28e 100644
--- a/libopna/opnatimer.c
+++ b/libopna/opnatimer.c
@@ -2,6 +2,7 @@
 #include "opna.h"
 
 enum {
+  TIMERA_BITS = 10,
   TIMERB_SHIFT = 4,
   TIMERB_BITS = 8 + TIMERB_SHIFT,
 };
@@ -37,35 +38,66 @@ void opna_timer_writereg(struct opna_timer *timer, unsigned reg, unsigned val) {
   val &= 0xff;
   opna_writereg(timer->opna, reg, val);
   switch (reg) {
+  case 0x24:
+    timer->timera &= ~0xff;
+    timer->timera |= val;
+    break;
+  case 0x25:
+    timer->timera &= 0xff;
+    timer->timera |= ((val & 3) << 8);
+    break;
   case 0x26:
     timer->timerb = val;
     timer->timerb_cnt = timer->timerb << TIMERB_SHIFT;
     break;
   case 0x27:
+    timer->timera_load = val & (1<<0);
+    timer->timera_enable = val & (1<<2);
     timer->timerb_load = val & (1<<1);
     timer->timerb_enable = val & (1<<3);
+    
+    if (val & (1<<4)) {
+      timer->status &= ~(1<<0);
+    }
     if (val & (1<<5)) {
       //timer->timerb_cnt = timer->timerb << TIMERB_SHIFT;
       timer->status &= ~(1<<1);
     }
   }
 }
-
+#include <stdio.h>
+#include <stdlib.h>
 void opna_timer_mix(struct opna_timer *timer, int16_t *buf, unsigned samples) {
   do {
     unsigned generate_samples = samples;
-    if (timer->timerb_enable) {
+    if (timer->timerb_enable && timer->timerb_load) {
       unsigned timerb_samples = (1<<TIMERB_BITS) - timer->timerb_cnt;
       if (timerb_samples < generate_samples) {
         generate_samples = timerb_samples;
       }
     }
+    if (timer->timera_enable && timer->timera_load) {
+      unsigned timera_samples = (1<<TIMERA_BITS) - timer->timera;
+      if (timera_samples < generate_samples) {
+        generate_samples = timera_samples;
+      }
+    }
     opna_mix(timer->opna, buf, generate_samples);
     if (timer->mix_cb) {
       timer->mix_cb(timer->mix_userptr, buf, generate_samples);
     }
     buf += generate_samples*2;
     samples -= generate_samples;
+    if (timer->timera_load) {
+      timer->timera = (timer->timera + generate_samples) & ((1<<TIMERA_BITS)-1);
+      if (!timer->timera && timer->timera_enable) {
+        if (!(timer->status & (1<<0))) {
+          timer->status |= (1<<0);
+          timer->interrupt_cb(timer->interrupt_userptr);
+        }
+      }
+      timer->timera &= (1<<TIMERA_BITS)-1;
+    }
     if (timer->timerb_load) {
       timer->timerb_cnt = (timer->timerb_cnt + generate_samples) & ((1<<TIMERB_BITS)-1);
       if (!timer->timerb_cnt && timer->timerb_enable) {
diff --git a/libopna/opnatimer.h b/libopna/opnatimer.h
index f3094ba..ad0fe0b 100644
--- a/libopna/opnatimer.h
+++ b/libopna/opnatimer.h
@@ -20,7 +20,10 @@ struct opna_timer {
   void *interrupt_userptr;
   opna_timer_mix_cb_t mix_cb;
   void *mix_userptr;
+  uint16_t timera;
   uint8_t timerb;
+  bool timera_load;
+  bool timera_enable;
   bool timerb_load;
   bool timerb_enable;
   uint16_t timerb_cnt;
-- 
cgit v1.2.3