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, offset;
 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                 offset = (soundCPU.RdMem(addr + 0) << 8) | soundCPU.RdMem(addr + 1);
 120                 addr += 2;
 121                 sprintf(outbuf, "%s $%04X  ", mnemonics[opcode], offset);
 122                 break;
 123         case 3:                                                                                         // Relative
 124 //              sprintf(outbuf, "%s $%04X", mnemonics[opcode], ++addr + (int16)(int8)soundCPU.RdMem(addr));
 125                 offset = addr + 1 + (int16)(int8)soundCPU.RdMem(addr);
 126                 addr++;
 127                 sprintf(outbuf, "%s $%04X  ", mnemonics[opcode], offset);
 128                 break;
 129         case 5:                                                                                         // Inherent
 130                 sprintf(outbuf, "%s        ", mnemonics[opcode]);
 131                 break;
 132         case 7:                                                                                         // Indexed
 133                 sprintf(outbuf, "%s $%02X,X  ", mnemonics[opcode], soundCPU.RdMem(addr++));
 134                 break;
 135         case 8:                                                                                         // Immediate
 136                 sprintf(outbuf, "%s #$%02X   ", mnemonics[opcode], soundCPU.RdMem(addr++));
 137                 break;
 138         case 9:                                                                                         // Long Immediate
 139 //              sprintf(outbuf, "%s #$%04X", mnemonics[opcode], (soundCPU.RdMem(addr++) << 8) | soundCPU.RdMem(addr++));
 140                 offset = (soundCPU.RdMem(addr + 0) << 8) | soundCPU.RdMem(addr + 1);
 141                 addr += 2;
 142                 sprintf(outbuf, "%s #$%04X ", mnemonics[opcode], offset);
 143                 break;
 144         }
 145
 146         DisplayBytes(pc, addr);                                                         // Show bytes
 147         WriteLog("%s", outbuf);                                                         // Display opcode & addressing, etc.
 148
 149         return addr - pc;
 150 }