From dfa0ec6be80dab9dc800724dd988d9c9584eeae9 Mon Sep 17 00:00:00 2001
From: Cacodemon345 <wahil1976@outlook.com>
Date: Mon, 4 Mar 2024 02:00:07 +0600
Subject: [PATCH] Implement ESS identification mixer register

---
 src/sound/snd_ess.c    | 21 +++++++++++++++++++--
 src/sound/snd_sb_dsp.c |  3 +++
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/sound/snd_ess.c b/src/sound/snd_ess.c
index f0f1b5ec7..9347a755e 100644
--- a/src/sound/snd_ess.c
+++ b/src/sound/snd_ess.c
@@ -76,6 +76,9 @@ typedef struct ess_mixer_t {
 
     uint8_t index;
     uint8_t regs[256];
+
+    uint8_t ess_id_str[4];
+    uint8_t ess_id_str_pos : 2;
 } ess_mixer_t;
 
 typedef struct ess_t {
@@ -128,6 +131,8 @@ ess_mixer_write(uint16_t addr, uint8_t val, void *priv)
     if (!(addr & 1)) {
         mixer->index      = val;
         mixer->regs[0x01] = val;
+        if (val == 0x40)
+            mixer->ess_id_str_pos = 0;
     } else {
         if (mixer->index == 0) {
             /* Reset */
@@ -218,8 +223,8 @@ ess_mixer_write(uint16_t addr, uint8_t val, void *priv)
 uint8_t
 ess_mixer_read(uint16_t addr, void *priv)
 {
-    const ess_t       *ess   = (ess_t *) priv;
-    const ess_mixer_t *mixer = &ess->mixer_sbpro;
+    ess_t       *ess   = (ess_t *) priv;
+    ess_mixer_t *mixer = &ess->mixer_sbpro;
 
     if (!(addr & 1))
         return mixer->index;
@@ -242,6 +247,11 @@ ess_mixer_read(uint16_t addr, void *priv)
         case 0x38:
             return mixer->regs[mixer->index];
 
+        case 0x40:
+            {
+                return mixer->ess_id_str[mixer->ess_id_str_pos++];
+            }
+
         default:
             //sb_log("ess: Unknown register READ: %02X\t%02X\n", mixer->index, mixer->regs[mixer->index]);
             break;
@@ -391,6 +401,13 @@ 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;
+        ess->mixer_sbpro.ess_id_str[2] = (addr >> 8) & 0xff;
+        ess->mixer_sbpro.ess_id_str[3] = addr & 0xff;
+    }
+
     return ess;
 }
 
diff --git a/src/sound/snd_sb_dsp.c b/src/sound/snd_sb_dsp.c
index 58131515d..45f8440a2 100644
--- a/src/sound/snd_sb_dsp.c
+++ b/src/sound/snd_sb_dsp.c
@@ -900,6 +900,9 @@ sb_exec_command(sb_dsp_t *dsp)
         case 0x10: /* 8-bit direct mode */
             sb_dsp_update(dsp);
             dsp->sbdat = dsp->sbdatl = dsp->sbdatr = (dsp->sb_data[0] ^ 0x80) << 8;
+            // FIXME: What does the ESS AudioDrive do to its filter/sample rate divider registers when emulating this Sound Blaster command?
+            ESSreg(0xA1) = 128 - (397700 / 22050);
+            ESSreg(0xA2) = 256 - (7160000 / (82 * ((4 * 22050) / 10)));
             break;
         case 0x14: /* 8-bit single cycle DMA output */
             sb_start_dma(dsp, 1, 0, 0, dsp->sb_data[0] + (dsp->sb_data[1] << 8));