From abc119b0b776bde0bed85d5246fce2058a506581 Mon Sep 17 00:00:00 2001
From: Michel Pollet <buserror@gmail.com>
Date: Sun, 29 Oct 2023 04:52:02 +0000
Subject: [PATCH] cpu: Added a few cycles here and there

This fixes the joystick reading loop

Signed-off-by: Michel Pollet <buserror@gmail.com>
---
 src/mii_65c02.c     | 19 ++++++++++++++++---
 src/mii_analog.c    |  7 +------
 test/mii_cpu_test.c | 18 ------------------
 3 files changed, 17 insertions(+), 27 deletions(-)

diff --git a/src/mii_65c02.c b/src/mii_65c02.c
index 65884c4..5ab5587 100644
--- a/src/mii_65c02.c
+++ b/src/mii_65c02.c
@@ -222,10 +222,10 @@ next_instruction:
 			_FETCH(cpu->PC++);	// relative branch
 			if (((cpu->_D >> d.s_bit) & 1) == d.s_bit_value) {
 				cpu->_P = cpu->PC + (int8_t)cpu->_P;
+				cpu->cycle++;
 				if ((cpu->_P & 0xff00) != (cpu->PC & 0xff00))
 					cpu->cycle++;
 				cpu->PC = cpu->_P;
-				cpu->cycle++;
 			}
 		}	break;
 		case 0x90: case 0xB0: case 0xF0: case 0x30:
@@ -241,7 +241,11 @@ next_instruction:
 		}	break;
 		case 0x80:
 		{	// BRA
-			cpu->PC = cpu->PC + (int8_t)cpu->_P; cpu->cycle++;
+			cpu->_P = cpu->PC + (int8_t)cpu->_P;
+			_FETCH(cpu->PC);// cpu->cycle++;
+			if ((cpu->_P & 0xff00) != (cpu->PC & 0xff00))
+				cpu->cycle++;
+			cpu->PC = cpu->_P;
 		}	break;
 		case 0x89:
 		{	// BIT immediate -- does not change N & V!
@@ -261,6 +265,7 @@ next_instruction:
 		}	break;
 		case 0x18: case 0xD8: case 0x58: case 0xB8:
 		{ // CLC, CLD, CLI, CLV
+			_FETCH(cpu->PC);
 			cpu->P.P[d.s_bit] = 0;
 		}	break;
 		case 0xC9: case 0xC5: case 0xD5: case 0xCD: case 0xDD:
@@ -284,18 +289,22 @@ next_instruction:
 		}	break;
 		case 0x3A:
 		{ // DEC
+			_FETCH(cpu->PC);
 			_NZ(--cpu->A);
 		}	break;
 		case 0xC6: case 0xD6: case 0xCE: case 0xDE:
 		{ // DEC
+			_FETCH(cpu->PC);
 			_NZ(--cpu->_D);
 		}	break;
 		case 0xCA:
 		{ // DEX
+			_FETCH(cpu->PC);
 			_NZ(--cpu->X);
 		}	break;
 		case 0x88:
 		{ // DEY
+			_FETCH(cpu->PC);
 			_NZ(--cpu->Y);
 		}	break;
 		case 0x49: case 0x45: case 0x55: case 0x4D: case 0x5D:
@@ -306,18 +315,22 @@ next_instruction:
 		}	break;
 		case 0x1A:
 		{ // INC
+			_FETCH(cpu->PC);
 			_NZ(++cpu->A);
 		}	break;
 		case 0xE6: case 0xF6: case 0xEE: case 0xFE:
 		{ // INC
+			_FETCH(cpu->PC);
 			_NZ(++cpu->_D);
 		}	break;
 		case 0xE8:
 		{ // INX
+			_FETCH(cpu->PC);
 			_NZ(++cpu->X);
 		}	break;
 		case 0xC8:
 		{ // INY
+			_FETCH(cpu->PC);
 			_NZ(++cpu->Y);
 		}	break;
 		case 0x4C: case 0x6C: case 0x7C:
@@ -361,7 +374,7 @@ next_instruction:
 		}	break;
 		case 0xEA:
 		{ // NOP
-			cpu->cycle++;
+			_FETCH(cpu->PC);
 		}	break;
 		case 0x09: case 0x05: case 0x15: case 0x0D: case 0x1D:
 		case 0x19: case 0x01: case 0x11: case 0x12:
diff --git a/src/mii_analog.c b/src/mii_analog.c
index e56e4dc..335aa8b 100644
--- a/src/mii_analog.c
+++ b/src/mii_analog.c
@@ -39,14 +39,9 @@ mii_analog_access(
 		case 0xc070: {
 			// multiplying by mii->speed allows reading joystick in 'fast' mode,
 			// this basically simulate slowing down just for the joystick reading
-
-			/* TODO: According to various artivles, the multiplier ought
-			 * to be 11, but we're not making the count here, which means it's
-			 * likely the emulated core is missing a cycle for one instruction
-			 * somewhere... */
 			for (int i = 0; i < 4; i++) {
 				a->v[i].decay = mii->cycles +
-									((a->v[i].value * 10.10) * mii->speed);
+									((a->v[i].value * 11) * mii->speed);
 			//	printf("joystick %d: %d\n", i, a->v[i].value);
 			}
 		}	break;
diff --git a/test/mii_cpu_test.c b/test/mii_cpu_test.c
index 0a8626d..52f0318 100644
--- a/test/mii_cpu_test.c
+++ b/test/mii_cpu_test.c
@@ -440,24 +440,6 @@ int main()
 	_run_this("SED ADC 99", doSED_ADC(0x99, 1), 0x00, C | D, 0);
 	_run_this("SED ADC BD", doSED_ADC(0xBD, 0), 0x23, C | D, 0);
 
-	_run_this("LDA ($aa)",
-		"  LDA #$00\n"
-		"  TAY\n"
-		"  TYA\n"
-		"  STA $c064\n"
-		"  LDX #$00\n"
-		"  LDA $c070\n"
-		"  LDY #$00\n"
-		"  NOP\n"
-		"  NOP\n"
-		"l LDA $c064,X\n"
-		"  BPL end\n"
-		"  INY \n"
-		"  BNE l\n"
-		"  DEY \n"
-		"end BRK\n",
-		0xAA, N, 1);
-
 #if 0
 //	_run_this("SED ADC FF", doSED_ADC(0xFF, 0), 0x65, C | D | N, 0);