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 Newer versions of MESS basically do the same thing (they use a newer version of this library).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 #define _STATE_C
2 #include <stddef.h>
3 #include <malloc.h>
4 #include <stdio.h>
5 #include "wd279x.h"
6 #include "wd2010.h"
7 #include "keyboard.h"
8 #include "state.h"
10 int state_init(size_t base_ram_size, size_t exp_ram_size)
11 {
12 // Free RAM if it's allocated
13 if (state.base_ram != NULL)
14 free(state.base_ram);
15 if (state.exp_ram != NULL)
16 free(state.exp_ram);
18 // Initialise hardware registers
19 state.romlmap = false;
20 state.idmarw = state.dmaen = state.dmaenb = false;
21 state.dma_count = state.dma_address = 0;
22 state.pie = 0;
23 state.ee = 0;
24 state.leds = 0;
25 state.genstat = 0; // FIXME: check this
26 state.bsr0 = state.bsr1 = 0; // FIXME: check this
27 state.timer_enabled = state.timer_asserted = false;
28 // Allocate Base RAM, making sure the user has specified a valid RAM amount first
29 // Basically: 512KiB minimum, 2MiB maximum, in increments of 512KiB.
30 if ((base_ram_size < 512*1024) || (base_ram_size > 2048*1024) || ((base_ram_size % (512*1024)) != 0))
31 return -1;
32 state.base_ram = malloc(base_ram_size);
33 if (state.base_ram == NULL)
34 return -2;
35 state.base_ram_size = base_ram_size;
37 // Now allocate expansion RAM
38 // The difference here is that we can have zero bytes of Expansion RAM; we're not limited to having a minimum of 512KiB.
39 if ((exp_ram_size > 2048*1024) || ((exp_ram_size % (512*1024)) != 0))
40 return -1;
41 state.exp_ram = malloc(exp_ram_size);
42 if (state.exp_ram == NULL)
43 return -2;
44 state.exp_ram_size = exp_ram_size;
46 // Load ROMs
47 FILE *r14c, *r15c;
48 r14c = fopen("roms/14c.bin", "rb");
49 if (r14c == NULL) {
50 fprintf(stderr, "[state] Error loading roms/14c.bin.\n");
51 return -3;
52 }
53 r15c = fopen("roms/15c.bin", "rb");
54 if (r15c == NULL) {
55 fprintf(stderr, "[state] Error loading roms/15c.bin.\n");
56 return -3;
57 }
59 // get ROM file size
60 fseek(r14c, 0, SEEK_END);
61 size_t romlen = ftell(r14c);
62 fseek(r14c, 0, SEEK_SET);
63 fseek(r15c, 0, SEEK_END);
64 size_t romlen2 = ftell(r15c);
65 fseek(r15c, 0, SEEK_SET);
66 if (romlen2 != romlen) {
67 fprintf(stderr, "[state] ROMs are not the same size!\n");
68 return -3;
69 }
70 if ((romlen + romlen2) > ROM_SIZE) {
71 fprintf(stderr, "[state] ROM files are too large!\n");
72 return -3;
73 }
75 // sanity checks completed; load the ROMs!
76 uint8_t *romdat1, *romdat2;
77 romdat1 = malloc(romlen);
78 romdat2 = malloc(romlen2);
79 if (fread(romdat1, 1, romlen, r15c) != romlen) {
80 fprintf(stderr, "[state] Error reading ROM 15C.\n");
81 return -3;
82 }
83 if (fread(romdat2, 1, romlen2, r14c) != romlen) {
84 fprintf(stderr, "[state] Error reading ROM 14C.\n");
85 return -3;
86 }
88 // convert the ROM data
89 for (size_t i=0; i<(romlen + romlen2); i+=2) {
90 state.rom[i+0] = romdat1[i/2];
91 state.rom[i+1] = romdat2[i/2];
92 }
94 // TODO: if ROM buffer not filled, repeat the ROM data we read until it is (wraparound emulation)
96 // free the data arrays and close the files
97 free(romdat1);
98 free(romdat2);
99 fclose(r14c);
100 fclose(r15c);
102 // Initialise the disc controller
103 wd2797_init(&state.fdc_ctx);
104 // Initialise the keyboard controller
105 keyboard_init(&state.kbd);
107 return 0;
108 }
110 void state_done()
111 {
112 if (state.base_ram != NULL) {
113 free(state.base_ram);
114 state.base_ram = NULL;
115 }
117 if (state.exp_ram != NULL) {
118 free(state.exp_ram);
119 state.exp_ram = NULL;
120 }
122 // Deinitialise the disc controller
123 wd2797_done(&state.fdc_ctx);
124 wd2010_done(&state.hdc_ctx);
125 }