3 * (C) 2018 by Andreas Eversberg <jolly@eversberg.eu>
6 * This program is free software: you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation, either version 3 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
23 #include "../libsdl/print.h"
24 #include "../libcpu/m68k.h"
25 #include "../libcpu/execute.h"
26 #include "mercenary.h"
28 #define INITIAL_STACK 0x7fffa
29 #define RESET_VECTOR 0x5a16c
30 // #define RESET_VECTOR 0x5a1a4 /* strange reset vector that causes the player to fly around */
32 /* interrupt CPU execution at special break points and tell emulation what to do */
33 const struct cpu_stop mercenary_stop_at[] = {
34 { 0x5a826, STOP_AT_WAIT_VBL }, /* done with rendering, waiting for VBL */
35 { 0x55d8c, STOP_AT_WAIT_VBL }, /* after pressing 'HELP' key before showing menu line on benson */
36 { 0x56398, STOP_AT_WAIT_VBL }, /* waiting for menu command */
37 { 0x55d94, STOP_AT_WAIT_VBL }, /* after pressing 'HELP' key while showing menu line on benson */
38 { 0x563a6, STOP_AT_WAIT_VBL }, /* after pressing 'RETURN' while game waits for other key to resume */
39 { 0x52946, STOP_AT_WAIT_VBL }, /* after dying, waiting for VBL to fade out palette */
40 { 0x5408E, STOP_AT_PARSE_OBJECT }, /* an object is about to be rendered, process vertex data */
41 { 0x0, STOP_AT_END }, /* end */
44 extern const uint32_t mercenary3_hex[];
45 extern int mercenary3_hex_size;
47 void mercenary_load(void)
51 /* load game binary from constant to volatile memory */
52 for (i = 0; i < mercenary3_hex_size; i += 4) {
53 m68k_write_memory_32(i, mercenary3_hex[i / 4]);
57 void mercenary_patch(void)
60 m68k_write_memory_32(0x00000, INITIAL_STACK);
63 m68k_write_memory_32(0x00004, RESET_VECTOR);
65 /* patch away the function call that is outside chip memory
66 * is this a copy protection????
68 m68k_write_memory_16(0x5a17c, 0x4e71); /* nop */
69 m68k_write_memory_16(0x5a17e, 0x4e71); /* nop */
70 m68k_write_memory_16(0x5a180, 0x4e71); /* nop */
72 /* remove wait for VBL */
73 m68k_write_memory_16(0x5a82C, 0x4e71); /* nop */
75 /* reduce loop that waits for disk stepper to move */
76 if (m68k_read_memory_32(0x562f8) != 0x000091b0) {
77 print_error("expecting loop counter of 0x000091b0 here, please fix!\n");
80 m68k_write_memory_32(0x562f8, 1);
81 /* reduce loop that waits for disk side change */
82 if (m68k_read_memory_32(0x55f5c) != 0x0000d020) {
83 print_error("expecting loop counter of 0x0000d020 here, please fix!\n");
86 m68k_write_memory_32(0x55f5c, 1);
89 uint32_t mercenary_palette(void)
91 return m68k_read_memory_32(0x0072b0);
94 const char *mercenary_gamesavesuffix = ".m3save";