Shamusworld >> Repos - stargem2/blob - src/dis6808.cpp

   1 //
   2 // 6808 disassembler
   3 //
   4 // by James L. Hammons
   5 //
   6 // (c) 2004 Underground Software
   7 //
   8
   9 #include "dis6808.h"
  10
  11 #include <stdio.h>
  12 #include <string>
  13 #include "v6808.h"
  14 #include "log.h"
  15
  16 using namespace std;
  17
  18 // External shit
  19
  20 extern V6808REGS soundCPU;//Hm.
  21
  22 // Private globals variables
  23
  24 static char op_mat[256] = {
  25   0, 5, 0, 0, 0, 0, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
  26   5, 5, 0, 0, 0, 0, 5, 5, 0, 5, 0, 5, 0, 0, 0, 0,
  27   3, 0, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
  28   5, 5, 5, 5, 5, 5, 5, 5, 0, 5, 0, 5, 0, 0, 5, 5,
  29   5, 0, 0, 5, 5, 0, 5, 5, 5, 5, 5, 0, 5, 5, 0, 5,
  30   5, 0, 0, 5, 5, 0, 5, 5, 5, 5, 5, 0, 5, 5, 0, 5,
  31   7, 0, 0, 7, 7, 0, 7, 7, 7, 7, 7, 0, 7, 7, 7, 7,
  32   2, 0, 0, 2, 2, 0, 2, 2, 2, 2, 2, 0, 2, 2, 2, 2,
  33   8, 8, 8, 0, 8, 8, 8, 0, 8, 8, 8, 8, 9, 3, 9, 0,
  34   1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1,
  35   7, 7, 7, 0, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
  36   2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
  37   8, 8, 8, 0, 8, 8, 8, 0, 8, 8, 8, 8, 0, 0, 9, 0,
  38   1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1,
  39   7, 7, 7, 0, 7, 7, 7, 7, 7, 7, 7, 7, 0, 0, 7, 7,
  40   2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 2, 0, 0, 2, 2
  41 };
  42
  43 static char mnemonics[256][6] = {
  44   "???  ","NOP  ","???  ","???  ","???  ","???  ","TAP  ","TPA  ",
  45   "INX  ","DEX  ","CLV  ","SEV  ","CLC  ","SEC  ","CLI  ","SEI  ",
  46   "SBA  ","CBA  ","???  ","???  ","???  ","???  ","TAB  ","TBA  ",
  47   "???  ","DAA  ","???  ","ABA  ","???  ","???  ","???  ","???  ",
  48   "BRA  ","???  ","BHI  ","BLS  ","BCC  ","BCS  ","BNE  ","BEQ  ",
  49   "BVC  ","BVS  ","BPL  ","BMI  ","BGE  ","BLT  ","BGT  ","BLE  ",
  50   "TSX  ","INS  ","PULA ","PULB ","DES  ","TXS  ","PSHA ","PSHB ",
  51   "???  ","RTS  ","???  ","RTI  ","???  ","???  ","WAI  ","SWI  ",
  52   "NEGA ","???  ","???  ","COMA ","LSRA ","???  ","RORA ","ASRA ",
  53   "ASLA ","ROLA ","DECA ","???  ","INCA ","TSTA ","???  ","CLRA ",
  54   "NEGB ","???  ","???  ","COMB ","LSRB ","???  ","RORB ","ASRB ",
  55   "ASLB ","ROLB ","DECB ","???  ","INCB ","TSTB ","???  ","CLRB ",
  56   "NEG  ","???  ","???  ","COM  ","LSR  ","???  ","ROR  ","ASR  ",
  57   "ASL  ","ROL  ","DEC  ","???  ","INC  ","TST  ","JMP  ","CLR  ",
  58   "NEG  ","???  ","???  ","COM  ","LSR  ","???  ","ROR  ","ASR  ",
  59   "ASL  ","ROL  ","DEC  ","???  ","INC  ","TST  ","JMP  ","CLR  ",
  60   "SUBA ","CMPA ","SBCA ","???  ","ANDA ","BITA ","LDAA ","???  ",
  61   "EORA ","ADCA ","ORAA ","ADDA ","CPX  ","BSR  ","LDS  ","???  ",
  62   "SUBA ","CMPA ","SBCA ","???  ","ANDA ","BITA ","LDAA ","STAA ",
  63   "EORA ","ADCA ","ORAA ","ADDA ","CPX  ","???  ","LDS  ","STS  ",
  64   "SUBA ","CMPA ","SBCA ","???  ","ANDA ","BITA ","LDAA ","STAA ",
  65   "EORA ","ADCA ","ORAA ","ADDA ","CPX  ","JSR  ","LDS  ","STS  ",
  66   "SUBA ","CMPA ","SBCA ","???  ","ANDA ","BITA ","LDAA ","STAA ",
  67   "EORA ","ADCA ","ORAA ","ADDA ","CPX  ","JSR  ","LDS  ","STS  ",
  68   "SUBB ","CMPB ","SBCB ","???  ","ANDB ","BITB ","LDAB ","???  ",
  69   "EORB ","ADCB ","ORAB ","ADDB ","???  ","???  ","LDX  ","???  ",
  70   "SUBB ","CMPB ","SBCB ","???  ","ANDB ","BITB ","LDAB ","STAB ",
  71   "EORB ","ADCB ","ORAB ","ADDB ","???  ","???  ","LDX  ","STX  ",
  72   "SUBB ","CMPB ","SBCB ","???  ","ANDB ","BITB ","LDAB ","STAB ",
  73   "EORB ","ADCB ","ORAB ","ADDB ","???  ","???  ","LDX  ","STX  ",
  74   "SUBB ","CMPB ","SBCB ","???  ","ANDB ","BITB ","LDAB ","STAB ",
  75   "EORB ","ADCB ","ORAB ","ADDB ","???  ","???  ","LDX  ","STX  "
  76 };
  77
  78 //
  79 // Display bytes in mem in hex
  80 //
  81 static void DisplayBytes(uint16 src, uint32 dst)
  82 {
  83         WriteLog("%04X: ", src);
  84         uint8 cnt = 0;                                                                          // Init counter...
  85
  86         if (src > dst)
  87                 dst += 0x10000;                                                                 // That should fix the FFFF bug...
  88
  89         for(uint32 i=src; i<dst; i++)
  90         {
  91                 WriteLog("%02X ", soundCPU.RdMem(i));
  92                 cnt++;                                                                                  // Bump counter...
  93         }
  94
  95         for(int i=cnt; i<5; i++)                                                        // Pad the leftover spaces...
  96                 WriteLog("   ");
  97 }
  98
  99 //
 100 // Decode a 6808 instruction
 101 //
 102 int Decode6808(uint16 pc)
 103 {
 104         char outbuf[80];
 105
 106         uint16 addr = pc;
 107         uint8 opcode = soundCPU.RdMem(addr++);                          // Get the opcode
 108
 109         switch (op_mat[opcode])                                                         // Decode the addressing mode...
 110         {
 111         case 0:                                                                                         // Illegal
 112                 sprintf(outbuf, "???");
 113                 break;
 114         case 1:                                                                                         // Zero page
 115                 sprintf(outbuf, "%s $%02X", mnemonics[opcode], soundCPU.RdMem(addr++));
 116                 break;
 117         case 2:                                                                                         // Absolute
 118                 sprintf(outbuf, "%s $%04X", mnemonics[opcode], (soundCPU.RdMem(addr++) << 8) | soundCPU.RdMem(addr++));
 119                 break;
 120         case 3:                                                                                         // Relative
 121                 sprintf(outbuf, "%s $%04X", mnemonics[opcode], ++addr + (int16)(int8)soundCPU.RdMem(addr));
 122                 break;
 123         case 5:                                                                                         // Inherent
 124                 sprintf(outbuf, "%s ", mnemonics[opcode]);
 125                 break;
 126         case 7:                                                                                         // Indexed
 127                 sprintf(outbuf, "%s $%02X,X", mnemonics[opcode], soundCPU.RdMem(addr++));
 128                 break;
 129         case 8:                                                                                         // Immediate
 130                 sprintf(outbuf, "%s #$%02X", mnemonics[opcode], soundCPU.RdMem(addr++));
 131                 break;
 132         case 9:                                                                                         // Long Immediate
 133                 sprintf(outbuf, "%s #$%04X", mnemonics[opcode], (soundCPU.RdMem(addr++) << 8) | soundCPU.RdMem(addr++));
 134                 break;
 135         }
 136
 137         DisplayBytes(pc, addr);                                                         // Show bytes
 138         WriteLog("%s", outbuf);                                                         // Display opcode & addressing, etc.
 139
 140         return addr - pc;
 141 }