- [NEW] [zx_disk] SPECIFY command (0x03)

- [NEW] [zx_disk] SENSE DRIVE STATUS command (0x04)

zx_disk.cpp

@@ -0,0 +1,149 @@
+#include "zx_disk.h"
+#include "z80.h"
+#include <stdio.h>
+
+#define ZX_FDC_MODE_IDLE        0
+#define ZX_FDC_MODE_COMMAND     1
+#define ZX_FDC_MODE_EXECUTION   2
+#define ZX_FDC_MODE_RESULT      3
+
+#define ZX_FDC_COMMAND_MASK     0x1F
+#define ZX_FDC_COMMAND_SPECIFY  0x03
+#define ZX_FDC_COMMAND_SENSE_DRIVE_STATUS  0x04
+
+#define ZX_FDC_MAIN_DRIVE0_BUSY 1
+#define ZX_FDC_MAIN_DRIVE1_BUSY 2
+#define ZX_FDC_MAIN_DRIVE2_BUSY 4
+#define ZX_FDC_MAIN_DRIVE3_BUSY 8
+#define ZX_FDC_MAIN_BUSY        16
+#define ZX_FDC_MAIN_EXEC_MODE   32
+#define ZX_FDC_MAIN_DATA_DIR    64 // 0: CPU->FDC   1: FDC->CPU
+#define ZX_FDC_MAIN_DATA_READY  128
+
+
+namespace zx_disk
+{
+    uint8_t mode = ZX_FDC_MODE_IDLE;
+    uint8_t call_count = 0;
+
+    uint8_t main_status_register = 0x80;
+    uint8_t st0 = 0x00;
+    uint8_t st1 = 0x00;
+    uint8_t st2 = 0x00;
+    uint8_t st3 = 0x00;
+
+    uint8_t srt, hlt, hut, nd;
+
+    uint8_t current_head = 0;
+    uint8_t current_drive = 0;
+
+    int zx_fdc_main_status_port_in(int port);
+    int zx_fdc_data_port_in(int port);
+    void zx_fdc_data_port_out(int port, int val);
+
+    void init()
+    {
+        z80::connect_port(0x2ffd, 0xf002, zx_fdc_main_status_port_in, nullptr);
+        z80::connect_port(0x3ffd, 0xf002, zx_fdc_data_port_in, zx_fdc_data_port_out);
+    }
+
+    void reset()
+    {
+
+    }
+
+    int zx_fdc_main_status_port_in(int port)
+    {
+        printf("FDC port 0x2ffd IN\n");
+        return main_status_register;
+    }
+
+    void start_command(uint8_t command);
+
+    uint8_t (*process_current_command)(uint8_t) = nullptr;
+    uint8_t process_command_specify(uint8_t command);
+    uint8_t process_command_sense_drive_status(uint8_t command);
+
+    int zx_fdc_data_port_in(int port)
+    {
+        printf("FDC port 0x3ffd IN\n");
+        if (process_current_command) return process_current_command(0);
+        return 0;
+    }
+
+    void zx_fdc_data_port_out(int port, int val)
+    {
+        printf("FDC port 0x3ffd OUT: 0x%02x\n", val);
+        if (process_current_command)
+            process_current_command(val);
+        else
+            start_command(val & ZX_FDC_COMMAND_MASK);
+    }
+
+    void start_command(uint8_t command)
+    {
+        main_status_register |= ZX_FDC_MAIN_BUSY;
+        mode = ZX_FDC_MODE_COMMAND;
+        call_count = 1;
+        switch(command)
+        {
+            case ZX_FDC_COMMAND_SPECIFY:
+                process_current_command = process_command_specify;
+                break;
+            case ZX_FDC_COMMAND_SENSE_DRIVE_STATUS:
+                process_current_command = process_command_sense_drive_status;
+                break;
+            default:
+            {
+                mode = ZX_FDC_MODE_RESULT;
+                call_count = 0;
+            }
+        }
+    }
+
+    // ===================================================================
+    // FDC COMMAND: SPECIFY (0x03)
+    // ===================================================================
+    uint8_t process_command_specify(uint8_t command)
+    {
+        switch (call_count) {
+            case 1:
+                srt = (command & 0xf0) >> 4;
+                hut = command & 0x0f;
+                call_count++;
+                break;
+            case 2:
+                hlt = (command & 0xfe) >> 1;
+                nd = command & 0x01;
+                call_count=0;
+                process_current_command = nullptr;
+                mode = ZX_FDC_MODE_IDLE;
+                main_status_register &= ~ZX_FDC_MAIN_BUSY;
+                break;
+        }
+        return 0;
+    }
+
+    // ===================================================================
+    // FDC COMMAND: SENSE DRIVE STATUS (0x04)
+    // ===================================================================
+    uint8_t process_command_sense_drive_status(uint8_t command)
+    {
+        switch (mode)
+        {
+            case ZX_FDC_MODE_COMMAND:
+                current_head = (command & 0x4)>>2;
+                current_drive = command & 0x3;
+                call_count = 0;
+                mode = ZX_FDC_MODE_RESULT;
+                break;
+            case ZX_FDC_MODE_RESULT:
+                process_current_command = nullptr;
+                mode = ZX_FDC_MODE_IDLE;
+                main_status_register &= ~ZX_FDC_MAIN_BUSY;
+                return current_drive | (current_head<<2) | 0x38; // ST3
+        }
+        return 0;
+    }
+
+}

zx_disk.h

@@ -0,0 +1,7 @@
+#pragma once
+
+namespace zx_disk
+{
+    void init();
+    void reset();
+}

zx_system.cpp

@@ -6,6 +6,7 @@
 #include "zx_tape.h"
 #include "zx_speaker.h"
 #include "ay-3-8912.h"
+#include "zx_disk.h"
 #include <vector>
 
 namespace zx_system
@@ -77,6 +78,7 @@ namespace zx_system
                 speaker::init();
                 speaker::register_source(zx_ula::get_sample);
                 speaker::register_source(audio::get_sample);
+                zx_disk::init();
 
                 registerUpdatable(zx_tape::update);
                 registerUpdatable(audio::update);