From 58281520d31ac074970fc26d34f4574403ad53f6 Mon Sep 17 00:00:00 2001
From: Maxim Poliakovski <maximumspatium@googlemail.com>
Date: Wed, 1 Nov 2023 16:16:58 +0100
Subject: [PATCH] Implement writes to SCSI Pseudo-DMA register.

---
 devices/common/scsi/sc53c94.cpp | 15 +++++++++++++++
 devices/common/scsi/sc53c94.h   |  1 +
 devices/ioctrl/amic.cpp         |  5 ++++-
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/devices/common/scsi/sc53c94.cpp b/devices/common/scsi/sc53c94.cpp
index 2375167..4feebae 100644
--- a/devices/common/scsi/sc53c94.cpp
+++ b/devices/common/scsi/sc53c94.cpp
@@ -190,6 +190,21 @@ uint16_t Sc53C94::pseudo_dma_read()
     return data_word;
 }
 
+void Sc53C94::pseudo_dma_write(uint16_t data) {
+    this->fifo_push((data >> 8) & 0xFFU);
+    this->fifo_push(data & 0xFFU);
+
+    // update DMA status
+    if (this->is_dma_cmd) {
+        this->xfer_count -= 2;
+        if (!this->xfer_count) {
+            this->status |= STAT_TC; // signal zero transfer count
+            //this->cur_state = SeqState::XFER_END;
+            this->sequencer();
+        }
+    }
+}
+
 void Sc53C94::update_command_reg(uint8_t cmd)
 {
     if (this->on_reset && (cmd & 0x7F) != CMD_NOP) {
diff --git a/devices/common/scsi/sc53c94.h b/devices/common/scsi/sc53c94.h
index 3f1a93c..38d4251 100644
--- a/devices/common/scsi/sc53c94.h
+++ b/devices/common/scsi/sc53c94.h
@@ -164,6 +164,7 @@ public:
     uint8_t  read(uint8_t reg_offset);
     void     write(uint8_t reg_offset, uint8_t value);
     uint16_t pseudo_dma_read();
+    void     pseudo_dma_write(uint16_t data);
 
     // real DMA control
     void     real_dma_xfer(int direction);
diff --git a/devices/ioctrl/amic.cpp b/devices/ioctrl/amic.cpp
index 4de4d61..d0da4f2 100644
--- a/devices/ioctrl/amic.cpp
+++ b/devices/ioctrl/amic.cpp
@@ -223,7 +223,10 @@ void AMIC::write(uint32_t rgn_start, uint32_t offset, uint32_t value, int size)
         this->mace->write((offset >> 4) & 0x1F, value);
         return;
     case 0x10:
-        this->scsi->write((offset >> 4) & 0xF, value);
+        if (offset & 0x100)
+            this->scsi->pseudo_dma_write(value);
+        else
+            this->scsi->write((offset >> 4) & 0xF, value);
         return;
     case 0x14: // Sound registers
         switch(offset) {