inject.c

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/* A work-in-progess MEGA65 (Commodore 65 clone origins) emulator
   Part of the Xemu project, please visit: https://github.com/lgblgblgb/xemu
   Copyright (C)2016-2021 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 "inject.h"
#include "xemu/emutools_files.h"
#include "memory_mapper.h"
#include "vic4.h"
#include "xemu/emutools_hid.h"
#include "xemu/f011_core.h"
 
#define C64_BASIC_LOAD_ADDR     0x0801
#define C65_BASIC_LOAD_ADDR     0x2001
 
int inject_ready_check_status = 0;
 
static void *inject_ready_userdata;
static void (*inject_ready_callback)(void*);
static struct {
        Uint8 *stream;
        int   size;
        int   load_addr;
        int   c64_mode;
        int   run_it;
} prg;
static Uint8 *under_ready_p;
 
 
static XEMU_INLINE int get_screen_width ( void )
{
        // C65 $D031.7 VIC-III:H640 Enable C64 640 horizontal pixels / 80 column mode
        // Used to determine if C64 or C65 "power-on" screen
        // TODO: this should be revised in the future, as MEGA65 can other means have
        // different screens!!!
        return (vic_registers[0x31] & 0x80) ? 80 : 40;
}
 
 
static void _cbm_screen_write ( Uint8 *p, const char *s )
{
        while (*s) {
                if (*s == '@')
                        *p++ = 0;
                else if (*s >= 'a' && *s <= 'z')
                        *p++ = *s - 'a' + 1;
                else if (*s >= 'A' && *s <= 'Z')
                        *p++ = *s - 'A' + 1;
                else
                        *p++ = *s;
                s++;
        }
}
 
 
#define CBM_SCREEN_PRINTF(scrp, ...)    do {    \
        char __buffer__[80];                    \
        sprintf(__buffer__, ##__VA_ARGS__);     \
        _cbm_screen_write(scrp, __buffer__);    \
        } while (0)
 
 
static void prg_inject_callback ( void *unused )
{
        DEBUGPRINT("INJECT: hit 'READY.' trigger, about to inject %d bytes from $%04X." NL, prg.size, prg.load_addr);
        fdc_allow_disk_access(FDC_ALLOW_DISK_ACCESS);
        memcpy(main_ram + prg.load_addr, prg.stream, prg.size);
        clear_emu_events();     // clear keyboard & co state, ie for C64 mode, probably had MEGA key pressed still
        CBM_SCREEN_PRINTF(under_ready_p - get_screen_width() + 7, "<$%04X-$%04X,%d bytes>", prg.load_addr, prg.load_addr + prg.size - 1, prg.size);
        if (prg.run_it) {
                // We must modify BASIC pointers ... Important to know the C64/C65 differences!
                if (prg.c64_mode) {
                        main_ram[0x2D] =  prg.size + prg.load_addr;
                        main_ram[0x2E] = (prg.size + prg.load_addr) >> 8;
                } else {
                        main_ram[0xAE] =  prg.size + prg.load_addr;
                        main_ram[0xAF] = (prg.size + prg.load_addr) >> 8;
                        main_ram[0x82] =  prg.size + prg.load_addr;
                        main_ram[0x83] = (prg.size + prg.load_addr) >> 8;
                }
                // If program was detected as BASIC (by load-addr) we want to auto-RUN it
                CBM_SCREEN_PRINTF(under_ready_p, " ?\"@\":RUN:");
                KBD_PRESS_KEY(0x01);    // press RETURN
                under_ready_p[get_screen_width()] = 0x20;       // be sure no "@" (screen code 0) at the trigger position
                inject_ready_check_status = 100;        // go into special mode, to see "@" character printed by PRINT, to release RETURN by that trigger
        } else {
                // In this case we DO NOT press RETURN for user, as maybe the SYS addr is different, or user does not want this at all!
                CBM_SCREEN_PRINTF(under_ready_p, " SYS%d:REM **YOU CAN PRESS RETURN**", prg.load_addr);
        }
        free(prg.stream);
        prg.stream = NULL;
}
 
 
static void allow_disk_access_callback ( void *unused )
{
        DEBUGPRINT("INJECT: re-enable disk access on READY. prompt" NL);
        fdc_allow_disk_access(FDC_ALLOW_DISK_ACCESS);
}
 
 
int inject_register_ready_status ( const char *debug_msg, void (*callback)(void*), void *userdata )
{
        if (inject_ready_check_status) {
                DEBUGPRINT("WARNING: INJECT: cannot register 'READY.' event, already having one in progress!" NL);
                //return 1;
        }
        DEBUGPRINT("INJECT: registering 'READY.' event: %s" NL, debug_msg);
        inject_ready_userdata = userdata;
        inject_ready_callback = callback;
        inject_ready_check_status = 1;
        memset(main_ram + 1024, 0, 1024 * 3);   // be sure, no READY. can be seen already on the screen
        return 0;
}
 
 
void inject_register_allow_disk_access ( void )
{
        fdc_allow_disk_access(FDC_DENY_DISK_ACCESS);    // deny now!
        // register event for the READY. prompt for re-enable
        inject_register_ready_status("Disk access re-enabled", allow_disk_access_callback, NULL);
}
 
 
int inject_register_prg ( const char *prg_fn, int prg_mode )
{
        prg.stream = NULL;
        prg.size = xemu_load_file(prg_fn, NULL, 3, 0x1F800, "Cannot load PRG to be injected");
        if (prg.size < 3)
                goto error;
        prg.stream = xemu_load_buffer_p;
        xemu_load_buffer_p = NULL;
        prg.load_addr = prg.stream[0] + (prg.stream[1] << 8);
        prg.size -= 2;
        memmove(prg.stream, prg.stream + 2, prg.size);
        // TODO: needs to be fixed to check ROM boundary (or eg from addr zero)
        if (prg.load_addr + prg.size >= 0x1F800) {
                ERROR_WINDOW("Program to be injected is too large (%d bytes, load address: $%04X)\nFile: %s",
                        prg.size,
                        prg.load_addr,
                        prg_fn
                );
                goto error;
        }
        switch (prg_mode) {
                case 0: // auto detection
                        if (prg.load_addr == C64_BASIC_LOAD_ADDR) {
                                prg.c64_mode = 1;
                                prg.run_it = 1;
                        } else if (prg.load_addr == C65_BASIC_LOAD_ADDR) {
                                prg.c64_mode = 0;
                                prg.run_it = 1;
                        } else {
                                char msg[512];
                                snprintf(msg, sizeof msg, "PRG to load: %s\nCannot detect C64/C65 mode for non-BASIC (load address: $%04X) PRG, please specify:", prg_fn, prg.load_addr);
                                prg.c64_mode = QUESTION_WINDOW("C65|C64|Ouch, CANCEL!", msg);
                                if (prg.c64_mode != 0 && prg.c64_mode != 1)
                                        goto error;
                                prg.run_it = 0;
                        }
                        break;
                case 64:
                        prg.c64_mode = 1;
                        prg.run_it = (prg.load_addr == C64_BASIC_LOAD_ADDR);
                        break;
                case 65:
                        prg.c64_mode = 0;
                        prg.run_it = (prg.load_addr == C65_BASIC_LOAD_ADDR);
                        break;
                default:
                        ERROR_WINDOW("Invalid parameter for prg-mode!");
                        goto error;
        }
        DEBUGPRINT("INJECT: prepare for C6%c mode, %s program, $%04X load address, %d bytes from file: %s" NL,
                prg.c64_mode ? '4' : '5',
                prg.run_it ? "BASIC (RUNable)" : "ML (SYSable)",
                prg.load_addr,
                prg.size,
                prg_fn
        );
        clear_emu_events();
        if (prg.c64_mode)
                KBD_PRESS_KEY(0x75);    // "MEGA" key is hold down for C64 mode
        if (inject_register_ready_status("PRG memory injection", prg_inject_callback, NULL)) // prg inject does not use the userdata ...
                goto error;
        fdc_allow_disk_access(FDC_DENY_DISK_ACCESS);    // deny now, to avoid problem on PRG load while autoboot disk is mounted
        return 0;
error:
        if (prg.stream) {
                free(prg.stream);
                prg.stream = NULL;
        }
        return 1;
}
 
 
static const Uint8 ready_msg[] = { 0x12, 0x05, 0x01, 0x04, 0x19, 0x2E };        // "READY." in screen codes
 
 
static int is_ready_on_screen ( void )
{
        int width = get_screen_width();
        // TODO: this should be revised in the future, as MEGA65 can other means have
        // different screen starting addresses, and not even dependent on the 40/80 column mode!!!
        int start = (width == 80) ? 2048 : 1024;
        // Check every lines of the screen (not the "0th" line, because we need "READY." in the previous line!)
        // NOTE: I cannot rely on exact position as different ROMs can have different line position for the "READY." text!
        for (int i = 1; i < 23; i++) {
                // We need this pointer later, to "fake" a command on the screen
                under_ready_p = main_ram + start + i * width;
                // 0XA0 -> cursor is shown, and the READY. in the previous line
                if (*under_ready_p == 0xA0 && !memcmp(under_ready_p - width, ready_msg, sizeof ready_msg))
                        return 1;
        }
        return 0;
}
 
 
void inject_ready_check_do ( void )
{
        if (XEMU_LIKELY(!inject_ready_check_status))
                return;
        if (inject_ready_check_status == 1) {           // we're in "waiting for READY." phase
                if (is_ready_on_screen())
                        inject_ready_check_status = 2;
        } else if (inject_ready_check_status == 100) {  // special mode ...
                // This is used to check the @ char printed by our tricky RUN line to see it's time to release RETURN (or just simply clear all the keyboard)
                // Also check for 'READY.' if it's still there, run program running maybe cleared the screen and we'll miss '@'!
                // TODO: this logic is too error-proon! Consider for some timing only, ie wait some frames after virtually pressing RETURN then release it.
                int width = get_screen_width();
                if (under_ready_p[width] == 0x00 || memcmp(under_ready_p - width, ready_msg, sizeof ready_msg)) {
                        inject_ready_check_status = 0;
                        clear_emu_events();             // reset keyboard state & co
                        DEBUGPRINT("INJECT: clearing keyboard status on '@' trigger." NL);
                }
        } else if (inject_ready_check_status > 10) {
                inject_ready_check_status = 0;  // turn off "ready check" mode, we have our READY.
                inject_ready_callback(inject_ready_userdata);   // callback is activated now
        } else
                inject_ready_check_status++;            // we're "let's wait some time after READY." phase
}