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