b2 6502 simulator snippet

.c

//////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////
//
// Read/Absolute
//
//////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////

static void T1_R_ABS(M6502 *);
static void T2_R_ABS(M6502 *);
static void T3_R_ABS(M6502 *);

static void T0_R_ABS(M6502 *s) {
    /* T0 phase 2 */
    /* (decode - already done) */
    
    /* T1 phase 1 */
    s->abus.w=s->pc.w++;
    s->read=M6502ReadType_Instruction;
    s->tfn=&T1_R_ABS;
}

static void T1_R_ABS(M6502 *s) {
    /* T1 phase 2 */
    s->ad.b.l=s->dbus;
    
    /* T2 phase 1 */
    s->abus.w=s->pc.w++;
    s->read=M6502ReadType_Instruction;
    s->tfn=&T2_R_ABS;
}

static void T2_R_ABS(M6502 *s) {
    /* T2 phase 2 */
    s->ad.b.h=s->dbus;
    
    /* T3 phase 1 */
    s->abus.w=s->ad.w;
    s->read=M6502ReadType_Data;
    s->tfn=&T3_R_ABS;
    CheckForInterrupts(s);
}

static void T3_R_ABS(M6502 *s) {
    /* T3 phase 2 */
    s->data=s->dbus;
    (*s->ifn)(s);
    #ifdef _DEBUG
    s->ifn=NULL;
    #endif
    
    /* T0 phase 1 */
    M6502_NextInstruction(s);
}

//////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////
//
// Read/Indirect,X
//
//////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////

static void T1_R_INX(M6502 *);
static void T2_R_INX(M6502 *);
static void T3_R_INX(M6502 *);
static void T4_R_INX(M6502 *);
static void T5_R_INX(M6502 *);

static void T0_R_INX(M6502 *s) {
    /* T0 phase 2 */
    /* (decode - already done) */
    
    /* T1 phase 1 */
    s->abus.w=s->pc.w++;
    s->read=M6502ReadType_Instruction;
    s->tfn=&T1_R_INX;
}

static void T1_R_INX(M6502 *s) {
    /* T1 phase 2 */
    s->ia.b.l=s->dbus;
    
    /* T2 phase 1 */
    s->abus.w=s->ia.b.l;
    s->read=M6502ReadType_Uninteresting;
    s->tfn=&T2_R_INX;
}

static void T2_R_INX(M6502 *s) {
    /* T2 phase 2 */
    s->data=s->dbus;
    
    /* T3 phase 1 */
    s->abus.w=(uint8_t)(s->ia.b.l+s->x);
    s->read=M6502ReadType_Address;
    s->tfn=&T3_R_INX;
}

static void T3_R_INX(M6502 *s) {
    /* T3 phase 2 */
    s->ad.b.l=s->dbus;
    
    /* T4 phase 1 */
    s->abus.w=(uint8_t)(s->ia.b.l+s->x+1);
    s->read=M6502ReadType_Address;
    s->tfn=&T4_R_INX;
}

static void T4_R_INX(M6502 *s) {
    /* T4 phase 2 */
    s->ad.b.h=s->dbus;
    
    /* T5 phase 1 */
    s->abus.w=s->ad.w;
    s->read=M6502ReadType_Data;
    s->tfn=&T5_R_INX;
    CheckForInterrupts(s);
}

static void T5_R_INX(M6502 *s) {
    /* T5 phase 2 */
    s->data=s->dbus;
    (*s->ifn)(s);
    #ifdef _DEBUG
    s->ifn=NULL;
    #endif
    
    /* T0 phase 1 */
    M6502_NextInstruction(s);
}