'fixed' it

MCUME_pico/picocpc/cpc.cpp

@@ -29,9 +29,11 @@ extern "C" {
 
 uint8_t RAM[0x10000];      // 64k
 unsigned char* bitstream = 0; // 16k video ram to be used by PIO.
+unsigned char* bitstream_init_pos = 0;
 static Z80 CPU;
 bool interrupt_generated = false;
 int sline = 0;
+int cycles_left = 0;
 
 // Implementations of system-specific emuapi Init, Step etc. functions. 
 
@@ -45,9 +47,10 @@ void cpc_Init(void)
     {
         emu_SetPaletteEntry(palette[i].R, palette[i].G, palette[i].B, i);
     }
-    if (bitstream == 0) bitstream = (unsigned char *)emu_Malloc(WIDTH); //*HEIGHT
+    if (bitstream == 0) bitstream = (unsigned char *)emu_Malloc(WIDTH*HEIGHT); //*HEIGHT
+    bitstream_init_pos = bitstream;
 
-    //ResetZ80(&CPU, CYCLES_PER_FRAME);
+    ResetZ80(&CPU, CYCLES_PER_FRAME);
     memset(RAM, 0, sizeof(RAM));
 }
 
@@ -57,7 +60,7 @@ void cpc_Init(void)
 void cpc_Start(char* filename)
 {
     CPU.PC.W = 0x0000;
-    CPU.IFF = IFF_IM1;
+    //CPU.IFF = IFF_IM1;
     ga_config.lower_rom_enable = true;
     ga_config.upper_rom_enable = false;
     ga_config.interrupt_counter = 0;
@@ -69,40 +72,26 @@ void cpc_Start(char* filename)
 */
 void cpc_Step(void)
 {
-    int cycles_taken = 0;
-    int cycles_total = 0;
-    while(cycles_total < CYCLES_PER_FRAME)
-    {   
-        cycles_taken = Cycles[RdZ80(CPU.PC.W)]; 
-        ExecZ80(&CPU);    
-        cycles_total += cycles_taken;
-
-        for(int i = 0; i < cycles_taken / 4; i++)
-        {
-            crtc_step();
-            interrupt_generated = ga_step();
-
-            if(interrupt_generated)
-            {
-                printf("Interrupting!\n");
-                
-                IntZ80(&CPU, INT_IRQ);
-            }
-            
-        }
+    cycles_left = ExecZ80(&CPU, 24); // execute for the duration of 6 NOPs (maximum instruction length)
+    //printf("Executing %d times.\n", cycles_left/4);
+    for(int k = 0; k < (24 - cycles_left) / 4; k++)
+    {
         
-        emu_DrawLine8(bitstream, WIDTH, HEIGHT, sline);
+        crtc_step();
+        interrupt_generated = ga_step();
+        if(interrupt_generated)
+        {
+            // printf("Interrupting!\n");   
+            IntZ80(&CPU, INT_RST38);
+            ga_config.interrupt_counter &= 0x1f;
+        }
         if(is_hsync_active())
         {
-            //printf("HSYNC at scanline %d \n", sline);
             sline = (sline + 1) % NBLINES;
-        }     
-    }
-    // printf("HSYNC at scanline %d \n", sline);
+        }
+        emu_DrawLine8(bitstream, WIDTH, HEIGHT, sline);
+    }          
     
-    
-        
-    //}   
 }
 
 /**

MCUME_pico/picocpc/crtc.cpp

@@ -106,8 +106,8 @@ void write_crt_controller(unsigned short address, uint8_t value)
 {
     switch(address & 0xFF00)
     {
-        case 0xBC00: selected_register = value & 0b11111;
-        case 0xBD00: registers[selected_register] = value;
+        case 0xBC00: selected_register = value & 0b11111;break;
+        case 0xBD00: registers[selected_register] = value;break;
     }
 }
 

MCUME_pico/picocpc/ga.cpp

@@ -116,12 +116,12 @@ void address_to_pixels()
     for(int i = 0; i < 2; i++) 
     {
         uint16_t address = crtc_generate_addr() + i;
-        // printf("address from CRTC: %x \nRAM data: %x \n", address, RAM[address]);
         uint8_t encodedByte = RAM[address];
         uint8_t pixel0, pixel1, pixel2, pixel3;
         uint8_t* pixels = (uint8_t*) calloc(4, 8*sizeof(uint8_t));
         if(address >= 0xC000)
         {
+            //printf("address from CRTC: %x \nRAM data: %x \n", address, RAM[address]);
             switch(ga_config.screen_mode)
             {
                 case 0:

MCUME_pico/picocpc/picocpc.cpp

@@ -71,7 +71,7 @@ int main(void) {
         }
         else {
             emu_Step();   
-            tft.waitSync();
+            // tft.waitSync();
         }
         //int c = getchar_timeout_us(0);
         //switch (c) {

MCUME_pico/picocpc/processor/Z80.c

@@ -505,15 +505,15 @@ void ResetZ80(Z80 *R, register int Cycles)
 /** negative, and current register values in R.             **/
 /*************************************************************/
 #ifdef EXECZ80
-int ExecZ80(register Z80 *R) // , register int RunCycles
+int ExecZ80(register Z80 *R, register int RunCycles) // 
 {
   register byte I;
   register pair J;
 
-  // for(R->ICount=RunCycles;;)
-  // {
-  //   while(R->ICount>0)
-  //   {
+  for(R->ICount=RunCycles;;)
+  {
+    while(R->ICount>0)
+    {
 #ifdef DEBUG
       /* Turn tracing on when reached trap address */
       if(R->PC.W==R->Trap) R->Trace=1;
@@ -546,8 +546,8 @@ int ExecZ80(register Z80 *R) // , register int RunCycles
       R->ICount+=R->IBackup-1;
       /* Interrupt CPU if needed */
       if((R->IRequest!=INT_NONE)&&(R->IRequest!=INT_QUIT)) IntZ80(R,R->IRequest);
-  //   }
-  //  }
+    }
+   }
  }
 }
 #endif /* EXECZ80 */

MCUME_pico/picocpc/processor/Z80.h

@@ -116,7 +116,7 @@ void ResetZ80(register Z80 *R, register int Cycles);
 /** negative, and current register values in R.             **/
 /*************************************************************/
 #ifdef EXECZ80
-int ExecZ80(register Z80 *R); // ,register int RunCycles
+int ExecZ80(register Z80 *R,register int RunCycles); // 
 #endif
 
 /** IntZ80() *************************************************/