#include <stdio.h>

#define u8 unsigned char
#define u16 unsigned short

extern u8 A, X, Y, S, tmp; /* tmp is result for cmp/cpx/cpy */
extern u8 mem[1 << 16]; /* 64K */
extern u8 *stack; /* page 1 */

extern unsigned int wtmp; /* wide temporary for adc/sbc */

extern u8 CF, ZF, NF; /* flags should really be a bitfield, *shrug* */

extern void dump_state(void);
extern void dump_mem(int start, int end);

#define dump_zp() dump_mem(0, 0xff);
#define dump_stack() dump_mem(0x100, 0x1ff);
#define dump_page(x) dump_mem(x * 0x100, x * 0x100 + 0x1ff);

#define _ind_y(x) mem[Y + (mem[x] | (mem[x+1] << 8))]

#define setnz(x) ZF=!x; NF=(x&0x80)!=0;

#define pha() stack[S--] = A;
#define pla() A = stack[++S]; setnz(A);
#define php() stack[S--] = (NF<<7 | ZF<<1 | CF);
#define plp() tmp = stack[++S]; NF=(tmp&0x80)!=0 ; ZF=(tmp&0x02)!=0; CF=tmp&0x01;

#define lda_i(x) A=x; setnz(A);
#define ldy_i(x) Y=x; setnz(Y);
#define ldx_i(x) X=x; setnz(X);
#define lda(x) A=mem[x]; setnz(A);
#define ldx(x) X=mem[x]; setnz(X);
#define ldy(x) Y=mem[x]; setnz(Y);
#define lda_abs_x(x) A=mem[x+X]; setnz(A);
#define lda_abs_y(x) A=mem[x+Y]; setnz(A);
#define lda_ind_y(x) A=_ind_y(x); setnz(A);

#define sta(x) mem[x] = A;
#define sta_abs_x(x) mem[x + X] = A;
#define sta_abs_y(x) mem[x + Y] = A;
#define sta_ind_y(x) _ind_y(x) = A;

#define stx(x) mem[x] = X;
#define sty(x) mem[x] = Y;

#define sec() CF=1;
#define clc() CF=0;

#define tax() X=A; setnz(X);
#define tay() Y=A; setnz(Y);
#define txa() A=X; setnz(A);
#define tya() A=Y; setnz(A);
#define txs() S=X; setnz(S);
/* note: tsx doesn't affect flags */
#define tsx() X=S;

#define _ror(x) tmp=x&1; x>>=1; x|=(CF<<7); CF=tmp; setnz(x);
#define _rol(x) tmp=(x&0x80)!=0; x<<=1; x|=CF; CF=tmp; setnz(x);

#define ror_a() _ror(A);
#define rol_a() _rol(A);
#define ror(x) _ror(mem[x]);
#define rol(x) _rol(mem[x]);

#define _lsr(x) CF=x&1; x>>=1; setnz(x);
#define _asl(x) CF=(x&0x80)!=0; x<<=1; setnz(x);

#define lsr_a() _lsr(A);
#define asl_a() _asl(A);
#define lsr(x) _lsr(mem[x]);
#define asl(x) _asl(mem[x]);

#define inx() X++; setnz(X);
#define iny() Y++; setnz(Y);
#define dex() X--; setnz(X);
#define dey() Y--; setnz(Y);

#define inc(x) mem[x]++; setnz(mem[x]);
#define dec(x) mem[x]--; setnz(mem[x]);

#define jsr(x) x();
#define rts() return;

#define jmp(x) goto x;
#define bne(x) if(!ZF) goto x;
#define beq(x) if(ZF) goto x;
#define bcc(x) if(!CF) goto x;
#define bcs(x) if(CF) goto x;
#define bpl(x) if(!NF) goto x;
#define bmi(x) if(NF) goto x;

#define ora_i(x) A|=x; setnz(A);
#define ora(x) A|=mem[x]; setnz(A);

#define and_i(x) A&=x; setnz(A);
#define and(x) A&=mem[x]; setnz(A);
#define and_abx_x(x) A&=mem[x+X]; setnz(A);
#define and_abs_y(x) A&=mem[x+Y]; setnz(A);
#define and_ind_y(x) A&=_ind_y(x); setnz(A);

#define eor_i(x) A^=x; setnz(A);
#define eor(x) A^=mem[x]; setnz(A);

#define adc_i(x) wtmp=A+x+CF; A=wtmp&0xff; CF=(wtmp&0x100)!=0; setnz(A);
#define adc(x) adc_i(mem[x]);
#define adc_abs_x(x) adc_i(mem[x+X]);
#define adc_abs_y(x) adc_i(mem[x+Y]);
#define adc_ind_y(x) adc_i(_ind_y(x));

/* TODO: actually check this logic! */
#define _sub(dst,orig,c,operand) wtmp=orig+(operand^0xff)+c; dst=wtmp&0xff; CF=(wtmp&0x100)!=0; setnz(dst);

#define sbc_i(x) _sub(A,A,CF,x)
#define sbc(x) _sub(A,A,CF,mem[x])
#define cmp_i(x) _sub(tmp,A,1,x)
#define cpy_i(x) _sub(tmp,Y,1,x)
#define cpx_i(x) _sub(tmp,X,1,x)
#define cmp(x) cmp_i(mem[x])
#define cmp_abs_x(x) cmp_i(mem[x+X])
#define cpy(x) cpy_i(mem[x])
#define cpx(x) cpx_i(mem[x])

#define nop() {}

/* this should produce a compile error instead */
#define brk() nop()