fix status flag ordering shenanigans

1 files changed, 33 insertions, 23 deletions

diff --git a/cpu.c b/cpu.c
index 5d36d37..c7d25ef 100644
--- a/cpu.c
+++ b/cpu.c
@@ -326,13 +326,16 @@ brk(void)
 static void
 bvc(uint8_t arg)
 {
-        if (regs.status.overflow == 0)
+        //regs.status.overflow = (STATUS_TO_INT() & (1 << 6)) == 0;
+        //if (regs.status.overflow == 0)
+        if ((STATUS_TO_INT() & (1 << 6)) == 0)
                 regs.pc += arg;
 }
 
 static void
 bvs(uint8_t arg)
 {
+        regs.status.overflow = (STATUS_TO_INT() & (1 << 6)) != 0;
         if (regs.status.overflow == 1)
                 regs.pc += arg;
 }
@@ -559,11 +562,7 @@ pha(void)
 static void
 php(void)
 {
-        uint8_t status;
-
-        status = STATUS_TO_INT();
-
-        PUSH(status);
+        PUSH(STATUS_TO_INT() | (1 << 4));
 }
 
 static void
@@ -582,14 +581,14 @@ plp(void)
 
         status = PULL();
 
-        regs.status.carry = (status & (1 << 7)) != 0;
-        regs.status.zero = (status & (1 << 6)) != 0;
-        regs.status.interrupt_disable = (status & (1 << 5)) != 0;
-        regs.status.decimal_mode = (status & (1 << 4)) != 0;
-        regs.status.brk = (status & (1 << 3)) != 0;
-        regs.status.unused = (status & (1 << 2)) != 0;
-        regs.status.overflow = (status & (1 << 1)) != 0;
-        regs.status.negative = (status & 1) != 0;
+        regs.status.carry = (status & 1) != 0;
+        regs.status.zero = (status & (1 << 1)) != 0;
+        regs.status.interrupt_disable = (status & (1 << 2)) != 0;
+        regs.status.decimal_mode = (status & (1 << 3)) != 0;
+        regs.status.brk = 0;
+        regs.status.unused = 1;
+        regs.status.overflow = (status & (1 << 6)) != 0;
+        regs.status.negative = (status & (1 << 7)) != 0;
 }
 
 static void
@@ -771,12 +770,14 @@ interpret(void)
         uint16_t arg, mem, deref;
         uint32_t cycles_;
         enum addressing_mode mode;
+        struct registers regs_;
 
         for (;;) {
                 opcode = peek(regs.pc++);
                 cycles_ = cycles;
                 did_memwrite = 0;
                 status = STATUS_TO_INT();
+                regs_ = regs;
 
                 printf("%04X  %02X", regs.pc - 1, opcode);
 
@@ -928,23 +929,26 @@ interpret(void)
                         printf("ASL");
                         break;
                 case 0x90:
-                        mode = AM_IMM;
+                        mode = AM_REL;
                         arg = opcode_arg(mode);
                         bcc(arg);
+                        arg += regs_.pc + 1;
                         cycles += 2;
                         printf("BCC");
                         break;
                 case 0xb0:
-                        mode = AM_IMM;
+                        mode = AM_REL;
                         arg = opcode_arg(mode);
                         bcs(arg);
+                        arg += regs_.pc + 1;
                         cycles += 2;
                         printf("BCS");
                         break;
                 case 0xf0:
-                        mode = AM_IMM;
+                        mode = AM_REL;
                         arg = opcode_arg(mode);
                         beq(arg);
+                        arg += regs_.pc + 1;
                         cycles += 2;
                         printf("BEQ");
                         break;
@@ -989,23 +993,26 @@ interpret(void)
                         printf("BIT");
                         break;
                 case 0x30:
-                        mode = AM_IMM;
+                        mode = AM_REL;
                         arg = opcode_arg(mode);
                         bmi(arg);
+                        arg += regs_.pc + 1;
                         cycles += 2;
                         printf("BMI");
                         break;
                 case 0xd0:
-                        mode = AM_IMM;
+                        mode = AM_REL;
                         arg = opcode_arg(mode);
                         bne(arg);
+                        arg += regs_.pc + 1;
                         cycles += 2;
                         printf("BNE");
                         break;
                 case 0x10:
-                        mode = AM_IMM;
+                        mode = AM_REL;
                         arg = opcode_arg(mode);
                         bpl(arg);
+                        arg += regs_.pc + 1;
                         cycles += 2;
                         printf("BPL");
                         break;
@@ -1016,16 +1023,18 @@ interpret(void)
                         printf("\tBRK");
                         goto loop_exit;
                 case 0x50:
-                        mode = AM_IMM;
+                        mode = AM_REL;
                         arg = opcode_arg(mode);
                         bvc(arg);
+                        arg += regs_.pc + 1;
                         cycles += 2;
                         printf("BVC");
                         break;
                 case 0x70:
-                        mode = AM_IMM;
+                        mode = AM_REL;
                         arg = opcode_arg(mode);
                         bvs(arg);
+                        arg += regs_.pc + 1;
                         cycles += 2;
                         printf("BVS");
                         break;
@@ -1884,6 +1893,7 @@ interpret(void)
                         if (did_memwrite) printf(" = %02X\t\t\t", ret);
                         else printf("\t\t\t\t");
                         break;
+                case AM_REL:
                 case AM_ABS:
                         printf(" $%04X", arg);
                         if (did_memwrite) printf(" = %02X\t\t\t", ret);
@@ -1910,7 +1920,7 @@ interpret(void)
                 }
 
                 printf("A:%02X X:%02X Y:%02X P:%02X SP:%02X CYC:%d\n",
-                    regs.a, regs.x, regs.y, status, regs.sp, cycles_);
+                    regs_.a, regs_.x, regs_.y, status, regs_.sp, cycles_);
         }
 loop_exit:
 }