static void saturn_instruction(saturn_state *cpustate)
{
int reg, adr;
switch(READ_OP(cpustate)) {
case 0:
switch(READ_OP(cpustate)) {
case 0: saturn_return_xm_set(cpustate);break;
case 1: saturn_return(cpustate, 1);break;
case 2: saturn_return_carry_set(cpustate);break;
case 3: saturn_return_carry_clear(cpustate);break;
case 4: saturn_sethex(cpustate);break;
case 5: saturn_setdec(cpustate);break;
case 6: saturn_push_c(cpustate);break;
case 7: saturn_pop_c(cpustate);break;
case 8: saturn_clear_st(cpustate);break;
case 9: saturn_st_to_c(cpustate);break;
case 0xa: saturn_c_to_st(cpustate);break;
case 0xb: saturn_exchange_c_st(cpustate);break;
case 0xc: saturn_inc_p(cpustate);break;
case 0xd: saturn_dec_p(cpustate);break;
case 0xe: saturn_instruction_0e(cpustate);break;
case 0xf: saturn_return_interrupt(cpustate);break;
}
break;
case 1:
saturn_instruction_1(cpustate);
break;
case 2:
saturn_load_p(cpustate);
break;
case 3:
saturn_load_reg(cpustate, C);
break; // lc
case 4:
adr=READ_OP_DIS8(cpustate);
if (adr==0) {
saturn_return(cpustate, cpustate->carry);
}
else {
saturn_jump(cpustate, (cpustate->pc+adr-2)&0xfffff, cpustate->carry);
}
break;
case 5:
adr=READ_OP_DIS8(cpustate);
if (adr==0) {
saturn_return(cpustate, !cpustate->carry);
}
else {
saturn_jump(cpustate, (cpustate->pc+adr-2)&0xfffff,!cpustate->carry);
}
break;
case 6:
adr=READ_OP_DIS12(cpustate);
saturn_jump(cpustate, (cpustate->pc+adr-3)&0xfffff,1); break;
case 7:
adr=READ_OP_DIS12(cpustate);
saturn_call(cpustate, (adr+cpustate->pc)&0xfffff); break;
case 8:
saturn_instruction_8(cpustate);
break;
case 9:
saturn_instruction_9(cpustate);
break;
case 0xa:
saturn_instruction_a(cpustate);
break;
case 0xb:
saturn_instruction_b(cpustate);
break;
case 0xc:
switch (reg=READ_OP(cpustate)) {
case 0: case 1: case 2: case 3:
case 8: case 9: case 0xa: case 0xb:
saturn_add(cpustate, add_left[reg], BEGIN_A, COUNT_A, add_right[reg]);
break;
case 4: case 5: case 6: case 7:
saturn_add(cpustate, A+(reg&3), BEGIN_A, COUNT_A, A+(reg&3));
break;
case 0xc: case 0xd: case 0xe: case 0xf:
saturn_decrement(cpustate, A+(reg&3), BEGIN_A, COUNT_A);
break;
}
break;
case 0xd:
switch(reg=READ_OP(cpustate)) {
case 0: case 1: case 2: case 3:
saturn_clear(cpustate, A+reg, BEGIN_A, COUNT_A);
break; // a=0 a
case 4: case 5: case 6: case 7:
case 8: case 9: case 0xa: case 0xb:
saturn_copy(cpustate, reg_right[reg&7], BEGIN_A, COUNT_A, reg_left[reg&7]);
break; // a=b a
case 0xc: case 0xd: case 0xe: case 0xf:
saturn_exchange(cpustate, reg_left[reg&3], BEGIN_A, COUNT_A, reg_right[reg&3]);
break; // abex a
}
break;
case 0xe:
switch(reg=READ_OP(cpustate)) {
case 0: case 1: case 2: case 3:
case 8: case 9: case 0xa: case 0xb:
saturn_sub(cpustate, sub_left[reg], BEGIN_A, COUNT_A, sub_right[reg]);
break;
case 4: case 5: case 6: case 7:
saturn_increment(cpustate, A+(reg&3), BEGIN_A, COUNT_A);
break; // a=a+1 a
case 0xc: case 0xd: case 0xe: case 0xf:
saturn_sub2(cpustate, sub_left[reg], BEGIN_A, COUNT_A, sub_right[reg]);
break;
}
break;
case 0xf:
switch(reg=READ_OP(cpustate)) {
case 0: case 1: case 2: case 3:
saturn_shift_nibble_left(cpustate, A+reg,BEGIN_A, COUNT_A);
break; // asl a
case 4: case 5: case 6: case 7:
saturn_shift_nibble_right(cpustate, A+(reg&3),BEGIN_A, COUNT_A);
break; // asr a
case 8: case 9: case 0xa: case 0xb:
saturn_negate(cpustate, A+(reg&3),BEGIN_A, COUNT_A);
break; // A=-A a
case 0xc: case 0xd: case 0xe: case 0xf:
saturn_invert(cpustate, A+(reg&3),BEGIN_A, COUNT_A);
break; // A=-A-1 a
}
break;
}
}
static void saturn_instruction(void)
{
int reg, adr;
switch(READ_OP()) {
case 0:
switch(READ_OP()) {
case 0: saturn_return_xm_set();break;
case 1: saturn_return(1);break;
case 2: saturn_return_carry_set();break;
case 3: saturn_return_carry_clear();break;
case 4: saturn_sethex();break;
case 5: saturn_setdec();break;
case 6: saturn_push_c();break;
case 7: saturn_pop_c();break;
case 8: saturn_clear_st();break;
case 9: saturn_st_to_c();break;
case 0xa: saturn_c_to_st();break;
case 0xb: saturn_exchange_c_st();break;
case 0xc:
saturn_inc_p();
break;
case 0xd:
saturn_dec_p();
break;
case 0xf: saturn_return_interrupt();break;
case 0xe:
saturn_instruction_0e();
break;
}
break;
case 1:
saturn_instruction_1();
break;
case 2:
saturn_load_p();
break;
case 3: saturn_load_reg(C);break; /* lc */
case 4:
adr=READ_OP_DIS8();
if (adr==0) {
saturn_return(saturn.carry);
} else {
saturn_jump((saturn.pc+adr-2)&0xfffff, saturn.carry);
}
break;
case 5:
adr=READ_OP_DIS8();
if (adr==0) {
saturn_return(!saturn.carry);
} else {
saturn_jump((saturn.pc+adr-2)&0xfffff,!saturn.carry);
}
break;
case 6:
adr=READ_OP_DIS12();
saturn_jump((saturn.pc+adr-3)&0xfffff,1); break;
case 7:
adr=READ_OP_DIS12();
saturn_call((adr+saturn.pc)&0xfffff); break;
case 8:
saturn_instruction_8();
break;
case 9:
saturn_instruction_9();
break;
case 0xa:
saturn_instruction_a();
break;
case 0xb:
saturn_instruction_b();
break;
case 0xc:
switch (reg=READ_OP()) {
case 0: case 1: case 2: case 3:
case 8: case 9: case 0xa: case 0xb:
saturn_add(add_left[reg], BEGIN_A, COUNT_A, add_right[reg]);
break;
case 4: case 5: case 6: case 7:
saturn_shift_left(A+(reg&3), BEGIN_A, COUNT_A);
break;
case 0xc: case 0xd: case 0xe: case 0xf:
saturn_decrement(A+(reg&3), BEGIN_A, COUNT_A);
break;
}
break;
case 0xd:
switch(reg=READ_OP()) {
case 0: case 1: case 2: case 3:
saturn_clear(A+reg, BEGIN_A, COUNT_A);
break; /* a=0 a */
case 4: case 5: case 6: case 7:
case 8: case 9: case 0xa: case 0xb:
saturn_copy(reg_right[reg&7], BEGIN_A, COUNT_A, reg_left[reg&7]); /*correct */
break; /* a=b a */
case 0xc: case 0xd: case 0xe: case 0xf:
saturn_exchange(reg_left[reg&3], BEGIN_A, COUNT_A, reg_right[reg&3]);
break; /* abex a */
}
break;
case 0xe:
switch(reg=READ_OP()) {
case 0: case 1: case 2: case 3:
case 8: case 9: case 0xa: case 0xb:
saturn_sub(sub_left[reg], BEGIN_A, COUNT_A, S64_READ_A(sub_right[reg]));
break;
case 4: case 5: case 6: case 7:
saturn_increment(A+(reg&3), BEGIN_A, COUNT_A);
break; /* a=a+1 a */
case 0xc: case 0xd: case 0xe: case 0xf:
saturn_sub2(sub_left[reg], BEGIN_A, COUNT_A, S64_READ_A(sub_right[reg]));
break;
}
break;
case 0xf:
switch(reg=READ_OP()) {
case 0: case 1: case 2: case 3:
saturn_shift_nibble_left(A+reg,BEGIN_A, COUNT_A);
break; /* asl a */
case 4: case 5: case 6: case 7:
saturn_shift_nibble_right(A+(reg&3),BEGIN_A, COUNT_A);
break; /* asr a */
case 8: case 9: case 0xa: case 0xb:
saturn_invert(A+(reg&3),BEGIN_A, COUNT_A);
break; /* A=-A a */
case 0xc: case 0xd: case 0xe: case 0xf:
saturn_negate(A+(reg&3),BEGIN_A, COUNT_A);
break; /* A=-A-1 a */
}
break;
}
}