Mercurial > repos > blastem
annotate m68k_util.c @ 2195:40290a923886
Implement Game Gear start button and region register
author | Michael Pavone <pavone@retrodev.com> |
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date | Sun, 21 Aug 2022 22:56:32 -0700 |
parents | 8494fe8d6b65 |
children | 414eb8c34198 |
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1 #include <string.h> |
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2 |
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3 void m68k_read_8(m68k_context *context) |
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4 { |
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5 context->cycles += 4 * context->opts->gen.clock_divider; |
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6 context->scratch1 = read_byte(context->scratch1, context->mem_pointers, &context->opts->gen, context); |
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7 } |
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8 |
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9 void m68k_read_16(m68k_context *context) |
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10 { |
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11 context->cycles += 4 * context->opts->gen.clock_divider; |
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12 context->scratch1 = read_word(context->scratch1, context->mem_pointers, &context->opts->gen, context); |
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13 } |
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14 |
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15 void m68k_write_8(m68k_context *context) |
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16 { |
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17 context->cycles += 4 * context->opts->gen.clock_divider; |
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18 write_byte(context->scratch2, context->scratch1, context->mem_pointers, &context->opts->gen, context); |
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19 } |
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20 |
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21 void m68k_write_16(m68k_context *context) |
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22 { |
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23 context->cycles += 4 * context->opts->gen.clock_divider; |
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24 write_word(context->scratch2, context->scratch1, context->mem_pointers, &context->opts->gen, context); |
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25 } |
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26 |
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27 void m68k_sync_cycle(m68k_context *context, uint32_t target_cycle) |
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28 { |
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29 //TODO: interrupt stuff |
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30 context->sync_cycle = target_cycle; |
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31 } |
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32 |
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33 void init_m68k_opts(m68k_options *opts, memmap_chunk * memmap, uint32_t num_chunks, uint32_t clock_divider) |
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34 { |
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35 memset(opts, 0, sizeof(*opts)); |
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36 opts->gen.memmap = memmap; |
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37 opts->gen.memmap_chunks = num_chunks; |
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38 opts->gen.address_mask = 0xFFFFFF; |
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39 opts->gen.byte_swap = 1; |
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40 opts->gen.max_address = 0x1000000; |
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41 opts->gen.bus_cycles = 4; |
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42 opts->gen.clock_divider = clock_divider; |
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43 } |
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44 |
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45 m68k_context *init_68k_context(m68k_options * opts, m68k_reset_handler reset_handler) |
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46 { |
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47 m68k_context *context = calloc(1, sizeof(m68k_context)); |
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48 context->opts = opts; |
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49 context->reset_handler = reset_handler; |
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50 context->int_cycle = 0xFFFFFFFFU; |
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51 return context; |
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52 } |
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53 |
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54 void m68k_reset(m68k_context *context) |
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55 { |
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56 //read initial SP |
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57 context->scratch1 = 0; |
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58 m68k_read_16(context); |
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59 context->aregs[7] = context->scratch1 << 16; |
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60 context->scratch1 = 2; |
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61 m68k_read_16(context); |
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62 context->aregs[7] |= context->scratch1; |
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63 |
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64 //read initial PC |
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65 context->scratch1 = 4; |
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66 m68k_read_16(context); |
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67 context->pc = context->scratch1 << 16; |
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68 context->scratch1 = 6; |
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69 m68k_read_16(context); |
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70 context->pc |= context->scratch1; |
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71 |
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72 context->scratch1 = context->pc; |
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73 m68k_read_16(context); |
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74 context->prefetch = context->scratch1; |
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75 context->pc += 2; |
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76 |
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77 context->status = 0x27; |
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78 } |
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79 |
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80 void m68k_print_regs(m68k_context *context) |
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81 { |
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82 printf("XNZVC\n%d%d%d%d%d\n", context->xflag != 0, context->nflag != 0, context->zflag != 0, context->vflag != 0, context->cflag != 0); |
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83 for (int i = 0; i < 8; i++) { |
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84 printf("d%d: %X\n", i, context->dregs[i]); |
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85 } |
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86 for (int i = 0; i < 8; i++) { |
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87 printf("a%d: %X\n", i, context->aregs[i]); |
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88 } |
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89 } |