From 6d3f2c478b97299c41d0735367b2e33069410b5f Mon Sep 17 00:00:00 2001
From: Kagamiin~ <kagamiin@riseup.net>
Date: Sat, 9 Mar 2024 19:14:36 -0300
Subject: [PATCH] Fix port 388h being disabled erroneously; set filter freq on
 sample rate change

---
 src/sound/snd_ess.c    | 30 +++++++++++++++---------------
 src/sound/snd_sb_dsp.c |  5 +++++
 2 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/src/sound/snd_ess.c b/src/sound/snd_ess.c
index 3de6615a3..f771ee6db 100644
--- a/src/sound/snd_ess.c
+++ b/src/sound/snd_ess.c
@@ -135,7 +135,6 @@ ess_mixer_write(uint16_t addr, uint8_t val, void *priv)
         mixer->regs[0x01] = val;
         if (val == 0x40)
         {
-            pclog("ess: Mixer addr 0x40 selected, ID string offset reset\n");
             mixer->ess_id_str_pos = 0;
         }
     } else {
@@ -211,20 +210,21 @@ ess_mixer_write(uint16_t addr, uint8_t val, void *priv)
                         uint16_t mpu401_base_addr = 0x300 | ((mixer->regs[0x40] << 1) & 0x30);
                         gameport_remap(ess->gameport, !(mixer->regs[0x40] & 0x2) ? 0x00 : 0x200);
 
-                        /* This doesn't work yet. */
-#if 1
-                        io_removehandler(0x0388, 0x0004,
-                                         ess->opl.read, NULL, NULL,
-                                         ess->opl.write, NULL, NULL,
-                                         ess->opl.priv);
-                        if ((mixer->regs[0x40] & 0x1) != 0)
+                        if (0)
                         {
-                            io_sethandler(0x0388, 0x0004,
-                                          ess->opl.read, NULL, NULL,
-                                          ess->opl.write, NULL, NULL,
-                                          ess->opl.priv);
+                            /* Not on ES1688. */
+                            io_removehandler(0x0388, 0x0004,
+                                            ess->opl.read, NULL, NULL,
+                                            ess->opl.write, NULL, NULL,
+                                            ess->opl.priv);
+                            if ((mixer->regs[0x40] & 0x1) != 0)
+                            {
+                                io_sethandler(0x0388, 0x0004,
+                                            ess->opl.read, NULL, NULL,
+                                            ess->opl.write, NULL, NULL,
+                                            ess->opl.priv);
+                            }
                         }
-#endif
                         switch ((mixer->regs[0x40] >> 5) & 0x7) {
                             case 0:
                                 mpu401_change_addr(ess->mpu, 0x00);
@@ -338,7 +338,7 @@ ess_mixer_read(uint16_t addr, void *priv)
 
             if (0)
             {
-                // not on ES1688
+                /* not on ES1688 */
                 uint8_t val = mixer->ess_id_str[mixer->ess_id_str_pos];
                 uint8_t pos_log = mixer->ess_id_str_pos; /* TODO remove */
                 mixer->ess_id_str_pos++;
@@ -475,6 +475,7 @@ ess_1688_init(UNUSED(const device_t *info))
     sb_dsp_setdma16_8(&ess->dsp, device_get_config_int("dma"));
     sb_dsp_setdma16_supported(&ess->dsp, 0);
     ess_mixer_reset(ess);
+
     /* DSP I/O handler is activated in sb_dsp_setaddr */
     {
         io_sethandler(addr, 0x0004,
@@ -502,7 +503,6 @@ ess_1688_init(UNUSED(const device_t *info))
 
     if (device_get_config_int("receive_input"))
         midi_in_handler(1, sb_dsp_input_msg, sb_dsp_input_sysex, &ess->dsp);
-
     {
         ess->mixer_sbpro.ess_id_str[0] = 0x16;
         ess->mixer_sbpro.ess_id_str[1] = 0x88;
diff --git a/src/sound/snd_sb_dsp.c b/src/sound/snd_sb_dsp.c
index fdcaf4587..3d150b9f9 100644
--- a/src/sound/snd_sb_dsp.c
+++ b/src/sound/snd_sb_dsp.c
@@ -716,6 +716,11 @@ static void sb_ess_write_reg(sb_dsp_t *dsp, uint8_t reg, uint8_t data)
                 dsp->sb_freq = 795500UL / (256ul - data);
             else
                 dsp->sb_freq = 397700UL / (128ul - data);
+            // TODO: check if this command updates the filter or not
+            sb_ess_update_filter_freq(dsp);
+            ESSreg(reg) = data; /* HACK: sb_ess_update_filter_freq updates 0xA1.
+                                 * I'm not sure if that could cause an off by one
+                                 * error, so this is just to be safe. */
             temp = 1000000.0 / dsp->sb_freq;
             dsp->sblatchi = dsp->sblatcho = TIMER_USEC * temp;
             dsp->sb_timei = dsp->sb_timeo;