From 72cec71303c9bd14b9c0cea0cf05a16ed8a15586 Mon Sep 17 00:00:00 2001
From: Joaquin <ioachim.radu@icloud.com>
Date: Sat, 17 Dec 2022 12:27:06 +0200
Subject: [PATCH] [cartridge] Fix mapper resolve address

    RenDev's latest commit cleaned the 4 bytes of buffer before the
    PRGROM even tho the program already accounted for that when
    calculating the return address by substracting 0x4. I'm leaving his
    way of dealing with the buffer since it saves 4 bytes of memory used
    for nothing in my implementation.

    Also cleaned the code a little, expect another commit that cleans
    the code more vigurously

    + Added debug-tickonclick Make rule for manual clock operation
---
 Makefile    |  3 +++
 bus.c       | 68 ++++++++++++++++++-----------------------------------
 cartridge.c | 20 +++++++---------
 cartridge.h |  2 +-
 4 files changed, 36 insertions(+), 57 deletions(-)

diff --git a/Makefile b/Makefile
index f0b9489..9e723cd 100644
--- a/Makefile
+++ b/Makefile
@@ -15,3 +15,6 @@ clean:
 	
 debug:
 	$(CC) $(CDEBUGFLAGS) bus.c cpu.c ppu.c cartridge.c -o $(OUTFILE)
+
+debug-tickonclick:
+	$(CC) $(CDEBUGFLAGS) -DTICKONKEY bus.c cpu.c ppu.c cartridge.c -o $(OUTFILE)
diff --git a/bus.c b/bus.c
index c4aa084..07def55 100644
--- a/bus.c
+++ b/bus.c
@@ -107,26 +107,21 @@ void activateCpuNmi(){
 }
 
 
-int main(int argc, char * argv[]){
 
-    #ifdef DEBUG
-        locationRegister testbit;
-        testbit.data = 0;
-        testbit.field.fineY = 0xFF;
-        printf("%016x", testbit.data);
-    #endif
 
-    activateCpuNmiBool = false;
 
-    CPU * cpu = (CPU*)malloc(sizeof(CPU)); //create new CPU
 
 
-    #ifdef DEBUG
-        if(cpu == NULL){
-            fprintf(stderr, "ERR: Out of RAM!\n");
-            exit(EXIT_FAILURE);
-        }
-    #endif
+
+
+
+
+
+int main(int argc, char * argv[]){
+
+    activateCpuNmiBool = false;
+
+    CPU * cpu = (CPU*)malloc(sizeof(CPU)); //create new CPU
 
     initCpu(cpu); //put new CPU in starting mode and dock it to the bus
 
@@ -137,35 +132,8 @@ int main(int argc, char * argv[]){
 
     //load the CHR and PRG banks from the .nes file (argv[1]), also loads the header for mapper construction
     initBanks(argv[1]);
-    cpu->PC = rom_start_address;
-
-    #ifdef DEBUG
-        //Test to see if writing to the bus is working correctly
-        busWrite8(0x0000, 0xFF);
-        printf("\n---- ---- %02X %02X\n", busRead8(0x0000), bus[0x0000]);
-
-
-        //open debug PC logfile
-        FILE * PClogFILE;
-        PClogFILE = fopen("PClogFILE", "w");
-    #endif
-
-    #ifdef DEBUG
-        //ppu tests
-        printf("\nCACA\n");
-        printf("\nt\n");
-        initPpu();
-        printf("\nk\n");
-        ppuRegWrite(0x2006, 0x00);
-        printf("\nok\n");
-        ppuRegWrite(0x2006, 0x10);
-        printf("\nok1\n");
-        ppuRegWrite(0x2007, 0x22);
-        printf("\nok2\n");
-        ppuRegWrite(0x2007, 0x33);
-        printf("\nok3\n");
-        dumpPpuBus();
-    #endif
+    //cpu->PC = romStartAddress; NOT FUNC YET
+    cpu->PC = 0xC000; 
 
 
     while(true){
@@ -180,10 +148,20 @@ int main(int argc, char * argv[]){
             cpuNmi(cpu);
             activateCpuNmiBool = false;
         }
+
+        //
+        //
         //RUN THE CPU CLOCK ONE TIME
         cpuClock(cpu);
+        //
+        //
+        //
+
+
         #ifdef DEBUG
-            getchar();
+            #ifdef TICKONKEY
+                getchar();
+            #endif
         #endif
     }
     
diff --git a/cartridge.c b/cartridge.c
index 9f2efab..2c5112c 100644
--- a/cartridge.c
+++ b/cartridge.c
@@ -7,7 +7,7 @@ byte CHRROM[0xFFFF];
 
 word not_handling_this = 0x100; //0xFF + 1
 
-word rom_start_address = 0x0;
+word romStartAddress = 0x0;
 
 void loadRomfileHeader(FILE * romfile){
     byte verificationToken[3] = "NES";
@@ -24,7 +24,7 @@ void loadRomfileHeader(FILE * romfile){
     for(byte i = 0; i < 5; i++){
         Header.flags.array[i] = getc(romfile);
     }
-    for(byte i = 0; i < 5; i++){ //Remove padding
+    for(byte i = 0; i < 4; i++){ //Remove padding
         getc(romfile);
     }
 }
@@ -33,12 +33,10 @@ void initBanks(char name[]){
     FILE * romfile;
     romfile = fopen(name, "rb");
 
-    #ifdef DEBUG
-        if(romfile == NULL){
-            fprintf(stderr, "ERR: file \"%s\" could not be opened for reading!\n", name);
-            exit(EXIT_FAILURE);
-        }
-    #endif
+    if(romfile == NULL){
+        fprintf(stderr, "ERR: file \"%s\" could not be opened for reading!\n", name);
+        exit(EXIT_FAILURE);
+    }
     
     loadRomfileHeader(romfile);
     
@@ -58,7 +56,7 @@ void initBanks(char name[]){
 
     //Read rom start Address
     #define ROM_START_VECTOR_ADDR (0xFFFC)
-    rom_start_address = busRead16(ROM_START_VECTOR_ADDR);
+    romStartAddress = busRead16(ROM_START_VECTOR_ADDR);
 }
 
 word mapper000_Read(word address, bool ppu){
@@ -67,9 +65,9 @@ word mapper000_Read(word address, bool ppu){
             return not_handling_this; //not_handling_this is a 16 bit data integer, no byte will return this ever so this is our "not handling this" return code
         }else{
             if(Header.PRG_BANKS > 1){ //32K model
-                return PRGROM[address - 0x8000 + 0x4];
+                return PRGROM[address - 0x8000];
             }else{ //16K model
-                return PRGROM[(address - 0x8000 + 0x4) % 0x3FFF];
+                return PRGROM[(address - 0x8000) % 0x3FFF];
             }
         }
     }else{ //if PPU
diff --git a/cartridge.h b/cartridge.h
index 5478ae4..62b7f3a 100644
--- a/cartridge.h
+++ b/cartridge.h
@@ -4,7 +4,7 @@
 //extern? void (*mapper_read)(word);
 //void (*mapper_write)(bool);
 
-extern word rom_start_address;
+extern word romStartAddress;
 
 #define K_SIZE 1024