Wed, 16 Apr 2014 02:20:43 -0600
fixed bus error handling for real this time (save registers before every instruction and push the saved registers if a bus error occurs, since the instruction may have changed registers before the bus error, and also stop the instruction immediately with longjmp so it won't change memory after the bus error)
This isn't actually what a real 68k does, but it is a good enough approximation. A real 68k will jump back into the middle of the faulted instruction and resume it from the memory access that faulted as opposed to restarting from the beginning like this CPU emulation does. It would be a lot harder to do that with the way this CPU library is designed. Newer versions of MESS basically do the same thing (they use a newer version of this library).
1 #ifndef _STATE_H
2 #define _STATE_H
4 #include <stddef.h>
5 #include <stdint.h>
6 #include <stdbool.h>
7 #include "wd279x.h"
8 #include "wd2010.h"
9 #include "keyboard.h"
11 // Maximum size of the Boot PROMs. Must be a binary power of two.
12 #define ROM_SIZE 32768
14 /**
15 * State error codes
16 */
17 typedef enum {
18 STATE_E_OK = 0, ///< Operation succeeded
19 STATE_E_BAD_RAMSIZE = -1, ///< Bad RAM size specified (not a multiple of 512K, or less than 512K)
20 STATE_E_NO_MEMORY = -2, ///< Out of memory while allocating state variables
21 STATE_E_ROM_LOAD_FAIL = -3 ///< Error loading ROMs
22 } STATE_ERR;
24 /**
25 * @brief Emulator state storage
26 *
27 * This structure stores the internal state of the emulator.
28 */
29 typedef struct {
30 // Boot PROM can be up to 32Kbytes total size
31 uint8_t rom[ROM_SIZE]; ///< Boot PROM data buffer
33 //// Main system RAM
34 uint8_t *base_ram; ///< Base RAM data buffer
35 size_t base_ram_size; ///< Size of Base RAM buffer in bytes
36 uint8_t *exp_ram; ///< Expansion RAM data buffer
37 size_t exp_ram_size; ///< Size of Expansion RAM buffer in bytes
39 /// Video RAM
40 uint8_t vram[0x8000];
42 /// Map RAM
43 uint8_t map[0x800];
45 //// Registers
46 uint16_t genstat; ///< General Status Register
47 uint16_t bsr0; ///< Bus Status Register 0
48 uint16_t bsr1; ///< Bus Status Register 1
50 //// MISCELLANEOUS CONTROL REGISTER
51 bool dma_reading; ///< True if Disc DMA reads from the controller, false otherwise
52 uint8_t leds; ///< LED status, 1=on, in order red3/green2/yellow1/red0 from bit3 to bit0
54 bool timer_enabled;
55 bool timer_asserted;
57 //// GENERAL CONTROL REGISTER
58 /// GENCON.ROMLMAP -- false ORs the address with 0x800000, forcing the
59 /// 68010 to access ROM instead of RAM when booting. TRM page 2-36.
60 bool romlmap;
61 /// GENCON.PIE -- Parity Error Check Enable
62 bool pie;
63 /// GENCON.EE -- Error Enable
64 bool ee;
66 /// DMA Address Register
67 uint32_t dma_address;
69 /// DMA count
70 uint32_t dma_count;
72 /// DMA direction
73 bool idmarw;
74 /// DMA enable
75 bool dmaen;
76 bool dmaenb;
78 /// DMA device selection flags
79 bool fd_selected;
80 bool hd_selected;
81 /// Floppy disc controller context
82 WD2797_CTX fdc_ctx;
83 /// Current disc image file
84 FILE *fdc_disc;
86 /// Hard disc controller context
87 WD2010_CTX hdc_ctx;
88 FILE *hdc_disc0;
89 FILE *hdc_disc1;
91 /// Keyboard controller context
92 KEYBOARD_STATE kbd;
93 } S_state;
95 // Global emulator state. Yes, I know global variables are evil, please don't
96 // email me and lecture me about it. -philpem
97 #ifndef _STATE_C
98 extern S_state state;
99 #else
100 S_state state;
101 #endif
103 /**
104 * @brief Initialise system state
105 *
106 * @param base_ram_size Base RAM size in bytes -- must be a multiple of 512KiB, min 512KiB, max 2MiB.
107 * @param exp_ram_size Expansion RAM size in bytes -- must be a multiple of 512KiB, min 0, max 2MiB.
108 *
109 * Initialises the emulator's internal state.
110 */
111 int state_init(size_t base_ram_size, size_t exp_ram_size);
113 /**
114 * @brief Deinitialise system state
115 *
116 * Deinitialises the saved state, and frees all memory. Call this function
117 * before exiting your program to avoid memory leaks.
118 */
119 void state_done();
121 #endif