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[#6] Give flag sets better names.
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@kosarev
kosarev committed Jun 20, 2021
1 parent 2acac30 commit bdeaae5
Showing 1 changed file with 24 additions and 24 deletions.
48 changes: 24 additions & 24 deletions z80.h
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Original file line number Diff line number Diff line change
Expand Up @@ -2418,44 +2418,44 @@ class i8080_executor : public internals::executor_base<B> {
fast_u8 hfb(fast_u8 ops12) {
return (ops12 << (base::hf_bit - 3)) & hf_mask; }

enum class flag_set { f1, f2, f3, f4, f5, f6, f7 };
enum class flag_set { adc, sbc, bitwise, set_cf, inc, dec, daa };

// Computes flags by given operands encoded as a 32-bit word.
// This function is supposed to take as much work from the
// core code executing instructions as possible, leaving there
// only those operations that can be performed very fast.
fast_u8 flags(fast_u8 f, flag_set fs, fast_u8 b, fast_u16 w) {
switch(fs) {
case flag_set::f1:
case flag_set::f2: {
case flag_set::adc:
case flag_set::sbc: {
fast_u16 res9 = w >> 1;
fast_u8 res8 = mask8(res9); // TODO: Can be just a cast?
fast_u8 cfv = mask8(w & 0x1); // TODO: Can be just a cast?
fast_u8 op1 = b & 0xf;
fast_u8 op2 = b >> 4;
fast_u8 hf = (fs == flag_set::f1) ? hfp(op1, op2, cfv) :
hfm(op1, op2, cfv);
fast_u8 hf = (fs == flag_set::adc) ? hfp(op1, op2, cfv) :
hfm(op1, op2, cfv);
return sf(res8) | zf(res8) | hf | pf(res8) | cfa(res9); }
case flag_set::f3: {
case flag_set::bitwise: {
fast_u8 res = mask8(w); // TODO: Can be just a cast?
fast_u8 ops12 = b;
return sf(res) | zf(res) | pf(res) | hfb(ops12); }
case flag_set::f4:
case flag_set::set_cf:
return static_cast<fast_u8>((f & ~cf_mask) | w);
case flag_set::f5:
case flag_set::f6: {
case flag_set::inc:
case flag_set::dec: {
fast_u8 n = b;
fast_u8 hf;
fast_u8 t;
if(fs == flag_set::f6) {
if(fs == flag_set::inc) {
hf = hfp(n, 1, 0);
t = mask8(n + 1);
} else {
hf = hfm(n, 1, 0);
t = mask8(n - 1);
}
return cf(f) | sf(t) | zf(t) | hf | pf(t); }
case flag_set::f7: {
case flag_set::daa: {
fast_u8 t = b;
fast_u8 flags = static_cast<fast_u8>(w);
return sf(t) | zf(t) | pf(t) | flags; }
Expand All @@ -2480,16 +2480,16 @@ class i8080_executor : public internals::executor_base<B> {
fast_u8 cfv = (k == alu::adc || k == alu::sbc) ? cf(f) : 0;
if(k <= alu::adc) {
t = a + n + cfv;
fs = flag_set::f1;
fs = flag_set::adc;
} else {
t = a - n - cfv;
fs = flag_set::f2;
fs = flag_set::sbc;
}
b = (n << 4) | (a & 0xf);
w = (t << 1) | cfv;
} else {
// AND, XOR, OR
fs = flag_set::f3;
fs = flag_set::bitwise;
if(k == alu::and_a) {
// Alexander Demin notes that the half-carry flag has
// its own special logic for the ANA and ANI
Expand Down Expand Up @@ -2520,7 +2520,7 @@ class i8080_executor : public internals::executor_base<B> {
fast_u32 r32 = i + n;
self().on_set_wz(inc16(i));
self().on_set_hl(mask16(r32));
self().on_flags_update(f, flag_set::f4, 0, r32 >> 16); }
self().on_flags_update(f, flag_set::set_cf, 0, r32 >> 16); }
void on_alu_r(alu k, reg r) {
do_alu(k, self().on_get_reg(r)); }
void on_call_cc_nn(condition cc, fast_u16 nn) {
Expand All @@ -2531,7 +2531,7 @@ class i8080_executor : public internals::executor_base<B> {
}
void on_ccf() {
fast_u8 f = self().on_get_f();
self().on_flags_update(f, flag_set::f4, 0, f ^ cf_mask); }
self().on_flags_update(f, flag_set::set_cf, 0, f ^ cf_mask); }
void on_cpl() {
self().on_set_a(self().on_get_a() ^ 0xff); }
void on_daa() {
Expand All @@ -2550,12 +2550,12 @@ class i8080_executor : public internals::executor_base<B> {
r = mask8(t2);

self().on_set_a(r);
self().on_flags_update(f, flag_set::f7, r, (hfv & hf_mask) | cfv); }
self().on_flags_update(f, flag_set::daa, r, (hfv & hf_mask) | cfv); }
void on_dec_r(reg r) {
fast_u8 n = self().on_get_reg(r);
fast_u8 f = self().on_get_f();
self().on_set_reg(r, mask8(n - 1));
self().on_flags_update(f, flag_set::f5, n, 0); }
self().on_flags_update(f, flag_set::dec, n, 0); }
void on_di() {
self().set_iff_on_di(false); }
void on_ei() {
Expand Down Expand Up @@ -2583,7 +2583,7 @@ class i8080_executor : public internals::executor_base<B> {
fast_u8 n = self().on_get_reg(r);
fast_u8 f = self().on_get_f();
self().on_set_reg(r, mask8(n + 1));
self().on_flags_update(f, flag_set::f6, n, 0); }
self().on_flags_update(f, flag_set::inc, n, 0); }
void on_ld_r_n(reg r, fast_u8 n) {
self().on_set_reg(r, n); }
void on_ld_r_r(reg rd, reg rs) {
Expand Down Expand Up @@ -2624,28 +2624,28 @@ class i8080_executor : public internals::executor_base<B> {
fast_u8 f = self().on_get_f();
fast_u8 r = mask8(a << 1) | (f & cf_mask);
self().on_set_a(r);
self().on_flags_update(f, flag_set::f4, 0, a >> 7); }
self().on_flags_update(f, flag_set::set_cf, 0, a >> 7); }
void on_rra() {
fast_u8 a = self().on_get_a();
fast_u8 f = self().on_get_f();
fast_u8 r = (a >> 1) | ((f & cf_mask) << 7);
self().on_set_a(r);
self().on_flags_update(f, flag_set::f4, 0, a & 0x1); }
self().on_flags_update(f, flag_set::set_cf, 0, a & cf_mask); }
void on_rlca() {
fast_u8 a = self().on_get_a();
fast_u8 f = self().on_get_f();
a = rol8(a);
self().on_set_a(a);
self().on_flags_update(f, flag_set::f4, 0, a & 0x1); }
self().on_flags_update(f, flag_set::set_cf, 0, a & cf_mask); }
void on_rrca() {
fast_u8 a = self().on_get_a();
fast_u8 f = self().on_get_f();
a = ror8(a);
self().on_set_a(a);
self().on_flags_update(f, flag_set::f4, 0, a >> 7); }
self().on_flags_update(f, flag_set::set_cf, 0, a >> 7); }
void on_scf() {
fast_u8 f = self().on_get_f();
self().on_flags_update(f, flag_set::f4, 0, cf_mask); }
self().on_flags_update(f, flag_set::set_cf, 0, cf_mask); }

protected:
using base::self;
Expand Down

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