Interrupts stuff and refactoring

2 files changed, 181 insertions, 92 deletions

diff --git a/CoolGirl.v b/CoolGirl.v
index 5bdff5a..9338c34 100644
--- a/CoolGirl.v
+++ b/CoolGirl.v
@@ -27,6 +27,8 @@ module CoolGirl # (
       parameter USE_MAPPER_078 = 1,             // mapper #078 - Irem: Holy Diver and Uchuusen - Cosmo Carrier

       parameter USE_MAPPER_087 = 1,             // mapper #087 - Jaleco

       parameter USE_MAPPER_090 = 1,             // mapper #090 - JY (partical support): Aladdin only

+      parameter USE_MAPPER_090_ACCURATE_IRQ = 0,// mapper #090 accurate IRQs: for Super Mario World

+      parameter USE_MAPPER_090_MULTIPLIER = 0,  // mapper #090 multiplier: for Super Mario World protection check

       parameter USE_MAPPER_093 = 1,             // mapper #093 - Sunsoft-2: Shanghai, Fantasy Zone

       parameter USE_MAPPER_097 = 0,             // mapper #097 - IREM TAMS1: only Kaiketsu Yanchamaru

       parameter USE_MAPPER_112 = 0,             // mapper #112 - NTDEC

diff --git a/mappers.vh b/mappers.vh
index c489917..1939f1d 100644
--- a/mappers.vh
+++ b/mappers.vh
@@ -27,15 +27,23 @@
    reg four_screen = 0;

    reg lockout = 0;  

 

-   /*

+   // Multiplier

    reg [7:0] mul1;

    reg [7:0] mul2;

    wire [15:0] mul = mul1*mul2;

-   */

 

    // IRQ stuff

-   assign irq = (mmc3_irq_out | mmc5_irq_out | mapper18_irq_out | mapper65_irq_out | vrc4_irq_cpu_out | vrc3_irq_cpu_out | fme7_irq_out | mapper42_irq_out) ? 1'b0 : 1'bZ;

-   // for scanline-based interrupts, counts A12 rises after long A12 falls (MMC3)

+   assign irq = (

+      mmc3_irq_out | 

+      mmc5_irq_out | 

+      mapper18_irq_out | 

+      mapper65_irq_out | 

+      vrc4_irq_cpu_out | 

+      vrc3_irq_cpu_out | 

+      fme7_irq_out | 

+      mapper42_irq_out | 

+      mapper90_irq_out) ? 1'b0 : 1'bZ;

+   // for MMC3 scanline-based interrupts, counts A12 rises after long A12 falls

    reg mmc3_irq_enabled = 0;           // register to enable/disable counter

    reg [7:0] mmc3_irq_latch = 0;       // stores counter reload latch value

    reg [7:0] mmc3_irq_counter = 0;     // counter itself (downcounting)

@@ -44,7 +52,7 @@
    reg mmc3_irq_reload_clear = 0;      // flag to clear reload flag

    reg mmc3_irq_ready = 0;             // stores 1 when IRQ is ready (enabled and non-zero)

    reg mmc3_irq_out = 0;               // stores 1 when IRQ is triggered

-   // scanline counter, counts dummy PPU reads

+   // scanline counter, counts dummy PPU reads, detects v-blank automatically

    reg [3:0] ppu_rd_hi_time = 0;       // counts how log there is no reads from PPU to detect v-blank

    reg [1:0] ppu_nt_read_count;        // nametable read counter

    reg [7:0] scanline = 0;             // current scanline

@@ -86,29 +94,37 @@
    reg mapper42_irq_enabled = 0;       // register to enable/disable counter

    reg [14:0] mapper42_irq_value = 0;  // counter itself (upcounting)

    wire mapper42_irq_out = mapper42_irq_value[14] & mapper42_irq_value[13];

+   // for mapper #90, unfiltered PPU A12 counter

+   reg mapper90_irq_enabled = 0;       // register to enable/disable counter

+   //reg [7:0] mapper90_xor;             // XOR register (is not used actually)

+   reg [10:0] mapper90_irq_latch = 0;   // stores counter reload latch value

+   reg [10:0] mapper90_irq_counter = 0; // counter itself (downcounting)

+   reg mapper90_irq_reload = 0;        // flag to reload counter and prescaler from latch

+   reg mapper90_irq_reload_clear = 0;  // flag to clear reload flag

+   reg mapper90_irq_pending = 0;       // flag of pending IRQ

+   reg mapper90_irq_out = 0;           // stores 1 when IRQ is triggered

+   reg mapper90_irq_out_clear = 0;     // flag to clear pending flag

 

-	// Mapper specific stuff

+   // Mapper specific stuff

    // for MMC2/MMC4

    reg ppu_latch0 = 0;

    reg ppu_latch1 = 0;

-	// for MMC1

-	reg [5:0] mmc1_load_register;

-	// for MMC3

-	reg [2:0] mmc3_internal;

-	// for mapper #69

+   // for MMC1

+   reg [5:0] mmc1_load_register;

+   // for MMC3

+   reg [2:0] mmc3_internal;

+   // for mapper #69

    reg [3:0] mapper69_internal;

-	// for mapper #90

-   reg mapper90_xor;

-	// for mapper #112

-	reg [2:0] mapper112_internal;

+   // for mapper #112

+   reg [2:0] mapper112_internal;

    // for mapper #163

    reg mapper_163_latch;

-	reg [7:0] mapper163_r0;

-	reg [7:0] mapper163_r1;

-	reg [7:0] mapper163_r2;

-	reg [7:0] mapper163_r3;

-	reg [7:0] mapper163_r4;

-	reg [7:0] mapper163_r5;

+   reg [7:0] mapper163_r0;

+   reg [7:0] mapper163_r1;

+   reg [7:0] mapper163_r2;

+   reg [7:0] mapper163_r3;

+   reg [7:0] mapper163_r4;

+   reg [7:0] mapper163_r5;

    // to block two writes in a row 

    reg writed;

 

@@ -126,8 +142,8 @@
                {1'b1, mmc5_irq_out, ~new_screen, 6'b000000} :

          (USE_MAPPER_036 && mapper == 6'b011101 && {cpu_addr_in[14:13], cpu_addr_in[8]} == 3'b101) ? // Need by Strike Wolf, being simplified mapper, this cart still uses some TCX mapper features andrely on it

                {1'b1, 2'b00, prg_bank_a[3:2], 4'b00} :

-         //(USE_MAPPER_090_MUL && (mapper == 6'b001101) && (cpu_addr_in[14:0] == 15'h5800)) ? {1'b1, mul[7:0]} :

-         //(USE_MAPPER_090_MUL && (mapper == 6'b001101) && (cpu_addr_in[14:0] == 15'h5801)) ? {1'b1, mul[15:8]} :

+         (USE_MAPPER_090_MULTIPLIER && (mapper == 6'b001101) && (cpu_addr_in[14:0] == 15'h5800)) ? {1'b1, mul[7:0]} :

+         (USE_MAPPER_090_MULTIPLIER && (mapper == 6'b001101) && (cpu_addr_in[14:0] == 15'h5801)) ? {1'b1, mul[15:8]} :

          9'b000000000

       ): 9'b000000000;

       

@@ -215,27 +231,35 @@
    

    always @ (negedge m2)

    begin    

+      // for MMC3

+      if (mmc3_irq_reload_clear)

+         mmc3_irq_reload = 0;

+

       // IRQ for VRC4

-      if (USE_MAPPER_021_022_023_025 & USE_VRC4_INTERRUPTS & (mapper == 6'b011000) & (vrc4_irq_cpu_control[1]))

+      if (USE_MAPPER_021_022_023_025 & USE_VRC4_INTERRUPTS & (vrc4_irq_cpu_control[1]))

       begin

+         reg carry;

          // Cycle mode without prescaler is not used by any games? It's missed in fceux source code.

-         if (/*vrc4_irq_cpu_control[2]*/ 0) // cycle mode

+			/*

+         if (vrc4_irq_cpu_control[2]) // cycle mode

          begin

-            vrc4_irq_cpu_value[7:0] = vrc4_irq_cpu_value[7:0] + 1'b1; // just count IRQ value

-            if (vrc4_irq_cpu_value[7:0] == 0)

+            {carry, vrc4_irq_cpu_value[7:0]} = vrc4_irq_cpu_value[7:0] + 1'b1; // just count IRQ value

+            if (carry)

             begin

                vrc4_irq_cpu_out = 1;

                vrc4_irq_cpu_value[7:0] = vrc4_irq_cpu_latch[7:0];

             end

-         end else begin // scanline mode

+         end else

+			*/

+			begin // scanline mode

             vrc4_irq_prescaler = vrc4_irq_prescaler + 1'b1; // count prescaler

             if ((vrc4_irq_prescaler_counter[1] == 0 && vrc4_irq_prescaler == 114) || (vrc4_irq_prescaler_counter[1] == 1 && vrc4_irq_prescaler == 113)) // 114, 114, 113

             begin

-               vrc4_irq_cpu_value[7:0] = vrc4_irq_cpu_value[7:0] + 1'b1;

                vrc4_irq_prescaler = 0;

                vrc4_irq_prescaler_counter = vrc4_irq_prescaler_counter + 1'b1;

                if (vrc4_irq_prescaler_counter == 2'b11) vrc4_irq_prescaler_counter =  2'b00;

-               if (vrc4_irq_cpu_value[7:0] == 0)

+               {carry, vrc4_irq_cpu_value[7:0]} = vrc4_irq_cpu_value[7:0] + 1'b1;

+               if (carry)

                begin

                   vrc4_irq_cpu_out = 1;

                   vrc4_irq_cpu_value[7:0] = vrc4_irq_cpu_latch[7:0];

@@ -245,7 +269,7 @@
       end

       

       // IRQ for VRC3

-      if (USE_MAPPER_073 & (mapper == 6'b010011) & (vrc3_irq_cpu_control[1]))

+      if (USE_MAPPER_073 & (vrc3_irq_cpu_control[1]))

       begin

          if (vrc3_irq_cpu_control[2])

          begin // 8-bit mode

@@ -266,31 +290,31 @@
       end      

 

       // IRQ for Sunsoft FME-7

-      if (USE_MAPPER_069 & (mapper == 6'b011001) & fme7_counter_enabled)

+      if (USE_MAPPER_069 & fme7_counter_enabled)

       begin

          if ((fme7_irq_value[15:0] == 0) & fme7_irq_enabled) fme7_irq_out = 1;

          fme7_irq_value[15:0] = fme7_irq_value[15:0] - 1'b1;

       end      

       

       // Mapper #18 - Sunsoft-2

-      if (USE_MAPPER_018 && mapper == 6'b000111)

+      if (USE_MAPPER_018)

       begin

          if (mapper18_irq_control[0])

          begin

             reg carry;

-            {carry, mapper18_irq_value[3:0]} = {1'b0, mapper18_irq_value[3:0]} - 1'b1;

+            {carry, mapper18_irq_value[3:0]} = mapper18_irq_value[3:0] - 1'b1;

             if (!mapper18_irq_control[3])

-               {carry, mapper18_irq_value[7:4]} = {1'b0, mapper18_irq_value[7:4]} - carry;

+               {carry, mapper18_irq_value[7:4]} = mapper18_irq_value[7:4] - carry;

             if (!mapper18_irq_control[3] && !mapper18_irq_control[2])

-               {carry, mapper18_irq_value[11:8]} = {1'b0, mapper18_irq_value[11:8]} - carry;

+               {carry, mapper18_irq_value[11:8]} = mapper18_irq_value[11:8] - carry;

             if (!mapper18_irq_control[3] && !mapper18_irq_control[2] && !mapper18_irq_control[1])

-               {carry, mapper18_irq_value[15:12]} = {1'b0, mapper18_irq_value[15:12]} - carry;

+               {carry, mapper18_irq_value[15:12]} = mapper18_irq_value[15:12] - carry;

             mapper18_irq_out = mapper18_irq_out | carry;

          end

       end

       

       // Mapper #65 - Irem's H3001

-      if (USE_MAPPER_065 && mapper == 6'b001110)

+      if (USE_MAPPER_065)

       begin

          if (mapper65_irq_enabled)

          begin

@@ -303,11 +327,22 @@
       end      

 

       // IRQ for mapper #42

-      if (USE_MAPPER_042 & USE_MAPPER_042_INTERRUPTS & (mapper == 6'b010111) & mapper42_irq_enabled)

+      if (USE_MAPPER_042 & USE_MAPPER_042_INTERRUPTS & mapper42_irq_enabled)

       begin

          mapper42_irq_value[14:0] = mapper42_irq_value[14:0] + 1'b1;

       end

-      

+

+      // for mapper #90

+      if (mapper90_irq_pending & !mapper90_irq_out_clear)

+      begin

+         mapper90_irq_out = 1;

+         mapper90_irq_out_clear = 1;

+      end else if (!mapper90_irq_pending) begin

+         mapper90_irq_out_clear = 0;

+      end

+      if (mapper90_irq_reload_clear)

+         mapper90_irq_reload = 0;

+         

       if (cpu_rw_in == 1) // read

       begin

          writed = 0;

@@ -345,7 +380,7 @@
             end

             

             // Mapper #163          

-            if (USE_MAPPER_163 && mapper == 6'b000110)

+            if (USE_MAPPER_163 && (mapper == 6'b000110))

             begin

                if (cpu_addr_in[14:0] == 15'h5101)

                begin

@@ -376,7 +411,7 @@
             end

             

             // Mapper #87

-            if (USE_MAPPER_087 && mapper == 6'b001100)

+            if (USE_MAPPER_087 && (mapper == 6'b001100))

             begin

                if (cpu_addr_in[14] & cpu_addr_in[13]) // $6000-$7FFF

                begin

@@ -385,18 +420,16 @@
             end

             

             // Mapper #90 - JY

-            /*

-            if (USE_MAPPER_090_MUL && mapper == 6'b001101)

+            if (USE_MAPPER_090_MULTIPLIER && (mapper == 6'b001101))

             begin

                if (cpu_addr_in[14:0] == 15'h5800)

                   mul1 = cpu_data_in;

                if (cpu_addr_in[14:0] == 15'h5801)

                   mul2 = cpu_data_in;

             end

-            */

 

             // MMC5

-            if (USE_MAPPER_005 && mapper == 6'b001111)

+            if (USE_MAPPER_005 && (mapper == 6'b001111))

             begin

                // just workaround for Castlevania 3, not real MMC5

                if (cpu_addr_in[14:0] == 15'h5105) // mirroring

@@ -461,7 +494,7 @@
             end            

             

             // Mapper #113 - NINA-03/06

-            if (USE_MAPPER_113 && mapper == 6'b011011)

+            if (USE_MAPPER_113 && (mapper == 6'b011011))

             begin             

                if ({cpu_addr_in[14:13], cpu_addr_in[8]} == 3'b101)

                begin

@@ -473,7 +506,7 @@
             end            

 

             // Mapper #133

-            if (USE_MAPPER_133 && mapper == 6'b011100)

+            if (USE_MAPPER_133 && (mapper == 6'b011100))

             begin             

                if ({cpu_addr_in[14:13], cpu_addr_in[8]} == 3'b101)

                begin

@@ -483,7 +516,7 @@
             end            

 

             // Mapper #184

-            if (USE_MAPPER_184 && mapper == 6'b011111)

+            if (USE_MAPPER_184 && (mapper == 6'b011111))

             begin             

                if (cpu_addr_in[14:13] == 2'b11)

                begin

@@ -538,7 +571,7 @@
             end

             

             // Mapper #78 - Holy Diver 

-            if (USE_MAPPER_078 && mapper == 6'b000011)

+            if (USE_MAPPER_078 && (mapper == 6'b000011))

             begin

                prg_bank_a[3:1] = cpu_data_in[2:0];

                chr_bank_a[6:3] = cpu_data_in[7:4];

@@ -546,21 +579,21 @@
             end

 

             // Mapper #97 - Irem's TAM-S1

-            if (USE_MAPPER_097 && mapper == 6'b000100)

+            if (USE_MAPPER_097 && (mapper == 6'b000100))

             begin

                prg_bank_a[5:1] = cpu_data_in[4:0];

                mirroring = {1'b0, ~cpu_data_in[7]};

             end

             

             // Mapper #93 - Sunsoft-2

-            if (USE_MAPPER_093 && mapper == 6'b000101)

+            if (USE_MAPPER_093 && (mapper == 6'b000101))

             begin

                prg_bank_a[3:1] = {cpu_data_in[6:4]};

                chr_write_enabled = cpu_data_in[0];

             end

             

             // Mapper #18 - Jaleco SS 88006

-            if (USE_MAPPER_018 && mapper == 6'b000111)

+            if (USE_MAPPER_018 && (mapper == 6'b000111))

             begin

                case ({cpu_addr_in[14:12], cpu_addr_in[1:0]})

                   5'b00000: prg_bank_a[3:0] = cpu_data_in[3:0]; // $8000

@@ -613,7 +646,7 @@
             end

             

             // Mapper #228 - Cheetahmen II            

-            if (USE_MAPPER_228 && mapper == 6'b001001)

+            if (USE_MAPPER_228 && (mapper == 6'b001001))

             begin

                prg_bank_a[5:2] = cpu_addr_in[10:7];

                chr_bank_a[7:3] = {cpu_addr_in[2:0], cpu_data_in[1:0]}; // only 256k, sorry

@@ -621,21 +654,21 @@
             end

             

             // Mapper #11 - ColorDreams

-            if (USE_MAPPER_011 && mapper == 6'b001010)

+            if (USE_MAPPER_011 && (mapper == 6'b001010))

             begin

                prg_bank_a[3:2] = cpu_data_in[1:0];

                chr_bank_a[6:3] = cpu_data_in[7:4];

             end

             

             // Mapper #66 - GxROM

-            if (USE_MAPPER_066 && mapper == 6'b001011)

+            if (USE_MAPPER_066 && (mapper == 6'b001011))

             begin

                prg_bank_a[3:2] = cpu_data_in[5:4];

                chr_bank_a[4:3] = cpu_data_in[1:0];             

             end

             

             // Mapper #90 - JY

-            if (USE_MAPPER_090 && mapper == 6'b001101)

+            if (USE_MAPPER_090 && (mapper == 6'b001101))

             begin

                if (cpu_addr_in[14:12] == 3'b000) // $800x

                begin

@@ -661,26 +694,50 @@
                end

                if ({cpu_addr_in[14:12], cpu_addr_in[1:0]} == 5'b10101) // $D001

                   mirroring = cpu_data_in[1:0];

-               if (cpu_addr_in[14:12] == 3'b100) // $C00x

+               if (USE_MAPPER_090_ACCURATE_IRQ)

                begin

-                  case (cpu_addr_in[2:0])

-                     3'b000: mmc3_irq_enabled = cpu_data_in[0];

-                     3'b001: ;

-                     3'b010: mmc3_irq_enabled = 0;

-                     3'b011: mmc3_irq_enabled = 1;

-                     3'b100: ;

-                     3'b101: begin

-                           mmc3_irq_latch = cpu_data_in ^ mapper90_xor;

-                           mmc3_irq_reload = 1;

-                        end

-                     3'b110: mapper90_xor = cpu_data_in;

-                     3'b111: ;                        

-                  endcase

+                  if (cpu_addr_in[14:12] == 3'b100) // $C00x

+                  begin

+                     case (cpu_addr_in[2:0])

+                        3'b000: mapper90_irq_enabled = cpu_data_in[0];

+                        3'b001: ;

+                        3'b010: mapper90_irq_enabled = 0;

+                        3'b011: mapper90_irq_enabled = 1;

+                        3'b100: begin

+                              mapper90_irq_latch[2:0] = cpu_data_in[2:0]; // ^ mapper90_xor[2:0];

+                              mapper90_irq_reload = 1;

+                           end

+                        3'b101: begin

+                              mapper90_irq_latch[10:3] = cpu_data_in; // ^ mapper90_xor;

+                              mapper90_irq_reload = 1;

+                           end

+                        3'b110: ;//mapper90_xor = cpu_data_in;

+                        3'b111: ;                        

+                     endcase

+                  end

+               end else begin

+                  // use MMC3's IRQs

+                  if (cpu_addr_in[14:12] == 3'b100) // $C00x

+                  begin

+                     case (cpu_addr_in[2:0])

+                        3'b000: mmc3_irq_enabled = cpu_data_in[0];

+                        3'b001: ;

+                        3'b010: mmc3_irq_enabled = 0;

+                        3'b011: mmc3_irq_enabled = 1;

+                        3'b100: ;

+                        3'b101: begin

+                              mmc3_irq_latch = cpu_data_in; // ^ mapper90_xor;

+                              mmc3_irq_reload = 1;

+                           end

+                        3'b110: ;//mapper90_xor = cpu_data_in;

+                        3'b111: ;                        

+                     endcase

+                  end

                end

             end

             

             // Mapper #65 - Irem's H3001

-            if (USE_MAPPER_065 && mapper == 6'b001110)

+            if (USE_MAPPER_065 && (mapper == 6'b001110))

             begin

                case ({cpu_addr_in[14:12], cpu_addr_in[2:0]})

                   6'b000000: prg_bank_a[5:0] = cpu_data_in[5:0]; // $8000

@@ -767,7 +824,7 @@
             

             // Mapper #9 and #10 - MMC2 and MMC4

             // flag0 - 0=MMC2, 1=MMC4

-            if (USE_MAPPER_009_010 && mapper == 6'b010001)

+            if (USE_MAPPER_009_010 && (mapper == 6'b010001))

             begin

                case (cpu_addr_in[14:12])

                   3'b010: if (~flags[0]) // $A000-$AFFF

@@ -783,7 +840,7 @@
             end

             

             // Mapper #152 - Bandai

-            if (USE_MAPPER_152 && mapper == 6'b010010)

+            if (USE_MAPPER_152 && (mapper == 6'b010010))

             begin

                chr_bank_a[6:3] = cpu_data_in[3:0];

                prg_bank_a[3:1] = cpu_data_in[6:4];

@@ -791,7 +848,7 @@
             end

       

             // Mapper #73 - VRC3

-            if (USE_MAPPER_073 && mapper == 6'b010011)

+            if (USE_MAPPER_073 && (mapper == 6'b010011))

             begin

                case (cpu_addr_in[14:12])

                   3'b000: vrc3_irq_cpu_latch[3:0] = cpu_data_in[3:0]; // $8000-$8FFF

@@ -935,7 +992,7 @@
             flag0 - switches A0 and A1 lines. 0=A0,A1 like VRC2b (mapper #23), 1=A1,A0 like VRC2a(#22), VRC2c(#25)

             flag1 - divides CHR bank select by two (mapper #22, VRC2a)

             */

-            if (USE_MAPPER_021_022_023_025 && mapper == 6'b011000)

+            if (USE_MAPPER_021_022_023_025 && (mapper == 6'b011000))

             begin

                case ({cpu_addr_in[14:12], flags[0] ? vrc_2b_low : vrc_2b_hi, flags[0] ? vrc_2b_hi : vrc_2b_low})

                   5'b00000,

@@ -1023,7 +1080,7 @@
             /*

             r0 - command register

             */          

-            if (USE_MAPPER_069 && mapper == 6'b011001)

+            if (USE_MAPPER_069 && (mapper == 6'b011001))

             begin

                if (cpu_addr_in[14:13] == 2'b00) mapper69_internal[3:0] = cpu_data_in[3:0];

                if (cpu_addr_in[14:13] == 2'b01)

@@ -1053,7 +1110,7 @@
             end

             

             // Mapper #32 - IREM G-101

-            if (USE_MAPPER_032 && mapper == 6'b011010)

+            if (USE_MAPPER_032 && (mapper == 6'b011010))

             begin

                case (cpu_addr_in[13:12])

                   2'b00: prg_bank_a[5:0] = cpu_data_in[5:0]; // PRG0

@@ -1075,7 +1132,7 @@
             end

             

             // Mapper #36 - TXC's PCB 01-22000-400

-            if (USE_MAPPER_036 && mapper == 6'b011101)

+            if (USE_MAPPER_036 && (mapper == 6'b011101))

             begin

                if (cpu_addr_in[14:1] != 14'b11111111111111)

                begin

@@ -1085,7 +1142,7 @@
             end

 

             // Mapper #70 - Bandai

-            if (USE_MAPPER_070 && mapper == 6'b011110)

+            if (USE_MAPPER_070 && (mapper == 6'b011110))

             begin

                prg_bank_a[4:1] = cpu_data_in[7:4];

                chr_bank_a[6:3] = cpu_data_in[3:0];

@@ -1093,38 +1150,47 @@
          end // romsel

       end // write

       

-     

-      // some IRQ stuff

+      // Some IRQ stuff

+

       // for MMC3

-      if (mmc3_irq_reload_clear)

-         mmc3_irq_reload = 0;

-      

       if (!mmc3_irq_enabled)

       begin

+         // ack

          mmc3_irq_ready = 0;

          mmc3_irq_out = 0;

-      end else if (mmc3_irq_enabled && mmc3_irq_counter != 0)

+      end else if (mmc3_irq_enabled && (mmc3_irq_counter != 0))

       begin

          // Fire scanline IRQ if counter is zero      

          // BUT doesn't fire it when it's zero end reenabled

          mmc3_irq_ready = 1;

-      end

-      else if (mmc3_irq_ready && mmc3_irq_counter == 0)

+      end else if (mmc3_irq_ready && (mmc3_irq_counter == 0))

       begin

          mmc3_irq_out = 1;

       end

+

+      // for mapper #90

+      if (USE_MAPPER_090 & USE_MAPPER_090_ACCURATE_IRQ & !mapper90_irq_enabled)

+      begin

+          mapper90_irq_out = 0;

+      end

+

       // for MMC5

-      if (USE_MAPPER_005 && romsel && cpu_addr_in[14:0] == 15'h5204) // write or read

-         mmc5_irq_ack = 1;         

-      if (mmc5_irq_ack && ~mmc5_irq_out)

-         mmc5_irq_ack = 0;

+      if (USE_MAPPER_005)

+      begin

+         if (romsel && (cpu_addr_in[14:0] == 15'h5204)) // write or read

+            mmc5_irq_ack = 1;         

+         if (mmc5_irq_ack && ~mmc5_irq_out)

+            mmc5_irq_ack = 0;

+      end

    end

    

    // IRQ counter

    always @ (posedge ppu_addr_in[12])

    begin 

+      // new scanline

       if (a12_low_time == 3)

       begin

+         // for MMC3

          if ((mmc3_irq_reload && !mmc3_irq_reload_clear) || (mmc3_irq_counter == 0))

          begin

             mmc3_irq_counter = mmc3_irq_latch;

@@ -1134,6 +1200,27 @@
          end

       end

       if (!mmc3_irq_reload) mmc3_irq_reload_clear = 0;    

+      

+      // for mapper #90

+      if (USE_MAPPER_090 & USE_MAPPER_090_ACCURATE_IRQ)

+      begin

+         if (mapper90_irq_out_clear) mapper90_irq_pending = 0;

+         if (mapper90_irq_reload && !mapper90_irq_reload_clear) 

+         begin

+            mapper90_irq_counter = mapper90_irq_latch;

+            mapper90_irq_reload_clear = 1;

+         end else if (!mapper90_irq_reload)

+         begin

+            mapper90_irq_reload_clear = 0;

+         end         

+         

+         if (mapper90_irq_enabled)

+         begin

+            reg carry;

+            {carry, mapper90_irq_counter} = mapper90_irq_counter - 1'b1;

+            mapper90_irq_pending = mapper90_irq_pending | carry;

+         end

+      end

    end

    

    // A12 must be low for 3 rises of M2