fake_rom.c

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/* RC2014 and generic Z80 SBC emulator
   Part of the Xemu project, please visit: https://github.com/lgblgblgb/xemu
   Copyright (C)2020 LGB (Gábor Lénárt) <lgblgblgb@gmail.com>
 
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
 
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
 
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
 
#include "xemu/emutools.h"
#include "hardware.h"
#include "fake_rom.h"
#include "console.h"
#include "uart.h"
 
 
 
static inline void start_shell ( const char *reason, int code )
{
        if (reason) {
                if (code != -1)
                        conprintf("ABORT: %s %d\r\n", reason, code);
                else
                        conprintf("ABORT: %s\r\n", reason);
        }
        Z80_PC = 2;
        Z80_SP = 0xFFFF;
}
 
 
static void api_call ( Uint8 sysnum )
{
        switch (sysnum) {
                case 0:
                        conputs("System RESET requested via API call.\r\n");
                        Z80_PC = 0;
                        break;
                case 1:
                        {
                        int r = console_input();
                        if (!r)
                                Z80_PC = 0x30;  // still waiting for character, loop back to the api call RST
                        else
                                Z80_A = r;
                        }
                        break;
                case 2:
                        console_output(Z80_A);
                        break;
                case 7:
                        conputs("\r\n");
                        break;
                default:
                        start_shell("Unknown/not-yet implemented API call C=", Z80_C);
                        break;
        }
}
 
 
void xrcrom_rst ( int n )
{
        console_io_traffic = 0;
        switch (n) {
                case 0: // RST 00
                        conputs("RESET, Xemu/RC2014 internal ROM\r\n(C)2020 LGB Gabor Lenart, part of the Xemu project.\r\n");
                        start_shell(NULL, -1);
                        break;
                case 6: // RST 30
                        api_call(Z80_C);
                        break;
                case 1: // RST 08
                case 2: // RST 10
                case 3: // RST 18
                case 4: // RST 20
                case 5: // RST 28
                case 7: // RST 38
                        start_shell("not implemented rst handler", n * 8);
                        break;
                default:
                        start_shell("UNKNOWN rst handler", n);
                        break;
        }
        io_cycles = console_io_traffic * cpu_cycles_per_uart_transfer;
        DEBUGPRINT("TIMING: %d I/O cycles" NL, io_cycles);
}
 
 
static void shell_execute ( char *cmd )
{
        conprintf("?%s\r\n", cmd);
}
 
 
static char command_buffer[127];
static int shell_mode;
 
void xrcrom_begin ( void )
{
        command_buffer[0] = 0;
        console_output('*');
        shell_mode = 0;
}
 
void xrcrom_run ( void )
{
        int r = console_input();
        Z80_PC = 4;
        if (r == 0)
                return;
        int command_size = strlen(command_buffer);
        if ((r == 8 || r == 127) && command_size) {
                conputs("\010 \010");
                command_buffer[command_size - 1] = 0;
                return;
        }
        if (command_size < 30 && r >= 32 && r < 127) {
                command_buffer[command_size] = r;
                command_buffer[command_size + 1] = 0;
                console_output(r);
                return;
        }
        if ((r == 13 || r == 10) && command_size) {
                conputs("\r\n");
                shell_execute(command_buffer);
                start_shell(NULL, -1);
                return;
        }
}