start implementing PPU

1 files changed, 21 insertions, 6 deletions

diff --git a/cpu.c b/cpu.c
index 8df2bf9..621fe5b 100644
--- a/cpu.c
+++ b/cpu.c
@@ -8,6 +8,7 @@
 #include "cpu.h"
 #include "opcodes.h"
 #include "rom.h"
+#include "ppu.h"
 
 #define MAX(a, b)       ((a > b) ? a : b)
 
@@ -146,14 +147,23 @@ opcode_mem(enum addressing_mode mode)
 }
 
 static void
+tick(void)
+{
+        cycles++;
+        ppu_tick();
+        ppu_tick();
+        ppu_tick();
+}
+
+static void
 branch(uint16_t addr, bool cond)
 {
         if (!cond)
                 return;
-        cycles++;
+        tick();
 
         if (((regs.pc + 1) & 0xFF00) != (addr & 0xFF00))
-                cycles++;
+                tick();
 
         regs.pc = addr;
 }
@@ -946,18 +956,21 @@ interpret(void)
 
                 while (spaces--) putchar(' ');
 
-                printf("A:%02X X:%02X Y:%02X P:%02X SP:%02X CYC:%d\n",
-                    regs.a, regs.x, regs.y, STATUS_TO_INT(), regs.sp, cycles);
+                printf("A:%02X X:%02X Y:%02X P:%02X SP:%02X PPU:%3d,%3d CYC:%d\n",
+                    regs.a, regs.x, regs.y, STATUS_TO_INT(), regs.sp,
+                    ppu.scanlines, ppu.cycles, cycles);
 
                 if (opcodes[op].memread)
                         opcodes[op].instr(peek(arg));
                 else
                         opcodes[op].instr(arg);
 
-                cycles += opcodes[op].cycles;
+                for (uint8_t i = 0; i < opcodes[op].cycles; i++)
+                        tick();
+
                 if (page_crossed) {
                         if (opcodes[op].page_cross)
-                                cycles++;
+                                tick();
                         page_crossed = false;
                 }
         }
@@ -976,6 +989,8 @@ cpu_init(void)
         regs.status.unused = 1;
 
         cycles += 7;
+        for (uint8_t i = 0; i < 7 * 3; i++)
+                ppu_tick();
 }
 
 int