Release 0.7.0.14

---------------- Added loading of 16x16 and 8x8 sprites in asset loader. Fixed a bug with sprites not shown when posY >= height - spriteSize or posX >= width - spriteSize. Fixed issue with WindowX and large tiles. Also fixed the off by 1 issue with small tiles. When resetting the machine, reset the tilestride... Fixed SBC (substraction) bug when in decimal mode and the subtrahend is larger than the minuend (difference is negative).
Trinity-11 · Nov 4, 2024 · f2fb052 · f2fb052
1 parent 9d3cda4
commit f2fb052
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Showing 5 changed files with 78 additions and 2 deletions.
diff --git a/FoenixIDETester/CpuTests.cs b/FoenixIDETester/CpuTests.cs
@@ -435,5 +435,44 @@ public void CheckContentOfBIsValid()
             Assert.AreEqual(0x1235, cpu.A.Value);
         }
 
+        /** 
+         * Bug reported by @Minstrel Dragon on Discord
+         * 
+         * I'll perform the test in 6502 mode
+         * 
+         * sed
+         * sec
+         * lda #$55
+         * sbc #$61
+         * 
+         * A register should contain #$94 
+         */
+        [TestMethod]
+        public void SubstractNegative()
+        {
+            ClearCarry();
+            // SED - switch to decimal
+            MemMgr.RAM.WriteByte(cpu.PC, OpcodeList.SED_Implied);
+            cpu.ExecuteNext();
+
+            // SEC - set the carry bit
+            MemMgr.RAM.WriteByte(cpu.PC, OpcodeList.SEC_Implied);
+            cpu.ExecuteNext();
+
+            // LDA #$55
+            MemMgr.RAM.WriteByte(cpu.PC, OpcodeList.LDA_Immediate);
+            MemMgr.RAM.WriteByte(cpu.PC + 1, 0x55);
+            cpu.ExecuteNext();
+
+            // SBC #$61
+            MemMgr.RAM.WriteByte(cpu.PC, OpcodeList.SBC_Immediate);
+            MemMgr.RAM.WriteByte(cpu.PC + 1, 0x61);
+            cpu.ExecuteNext();
+
+            // The result should be #$94
+            Assert.AreEqual(0x94, cpu.A.Value);
+
+        }
+
     }
 }
diff --git a/FoenixIDETester/app.config b/FoenixIDETester/app.config
@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="utf-8"?>
+<configuration>
+  <runtime>
+    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
+      <dependentAssembly>
+        <assemblyIdentity name="System.Runtime.CompilerServices.Unsafe" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
+        <bindingRedirect oldVersion="0.0.0.0-5.0.0.0" newVersion="5.0.0.0" />
+      </dependentAssembly>
+      <dependentAssembly>
+        <assemblyIdentity name="System.Memory" publicKeyToken="cc7b13ffcd2ddd51" culture="neutral" />
+        <bindingRedirect oldVersion="0.0.0.0-4.0.1.2" newVersion="4.0.1.2" />
+      </dependentAssembly>
+      <dependentAssembly>
+        <assemblyIdentity name="System.Collections.Immutable" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
+        <bindingRedirect oldVersion="0.0.0.0-8.0.0.0" newVersion="8.0.0.0" />
+      </dependentAssembly>
+      <dependentAssembly>
+        <assemblyIdentity name="System.Diagnostics.DiagnosticSource" publicKeyToken="cc7b13ffcd2ddd51" culture="neutral" />
+        <bindingRedirect oldVersion="0.0.0.0-8.0.0.1" newVersion="8.0.0.1" />
+      </dependentAssembly>
+      <dependentAssembly>
+        <assemblyIdentity name="System.Reflection.Metadata" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
+        <bindingRedirect oldVersion="0.0.0.0-8.0.0.1" newVersion="8.0.0.1" />
+      </dependentAssembly>
+    </assemblyBinding>
+  </runtime>
+</configuration>
diff --git a/Main/Processor/Operations.cs b/Main/Processor/Operations.cs
@@ -1013,7 +1013,16 @@ public void ExecuteSBC(byte instruction, AddressModes addressMode, int signature
             int val = GetValue(addressMode, signature, cpu.A.Width);
             int nv;
             if (cpu.Flags.Decimal)
-                nv = HexVal(BCDVal(cpu.A.Value) - BCDVal(val + 1) + cpu.Flags.CarryBit);
+            {
+                if (val < cpu.A.Value)
+                {
+                    nv = HexVal(BCDVal(cpu.A.Value) - BCDVal(val + 1) + cpu.Flags.CarryBit);
+                }
+                else
+                {
+                    nv = HexVal(0x64 + BCDVal(cpu.A.Value) - BCDVal(val + 1) + cpu.Flags.CarryBit);
+                }
+            }
             else
             {
                 nv = cpu.A.Value - val - 1 + cpu.Flags.CarryBit;

diff --git a/Main/Processor/Register.cs b/Main/Processor/Register.cs
@@ -32,7 +32,7 @@ public virtual int Value
         {
             get
             {
-                return byteLength == 1 ? (int)(this._value & 0xff) : this._value;
+                return byteLength == 1 ? (int)(this._value & 0xff) : this._value & 0xffff;
             }
 
             set

diff --git a/Release Notes.txt b/Release Notes.txt
@@ -4,6 +4,7 @@ Added loading of 16x16 and 8x8 sprites in asset loader.
 Fixed a bug with sprites not shown when posY >= height - spriteSize or posX >= width - spriteSize.  
 Fixed issue with WindowX and large tiles.  Also fixed the off by 1 issue with small tiles.
 When resetting the machine, reset the tilestride...
+Fixed SBC (substraction) bug when in decimal mode and the subtrahend is larger than the minuend (difference is negative).
 
 ** TODO: Users can now modify the CPU registers when in debug mode. The registers have a white background when editable.
 ** TODO: Implemented the various cursor modes and rates.
-Original file line number
+Diff line change
@@ Expand Up / @@ -32,7 +32,7 @@ public virtual int Value @@
             {
                 get
                 {
-                    return byteLength == 1 ? (int)(this._value & 0xff) : this._value;
+                    return byteLength == 1 ? (int)(this._value & 0xff) : this._value & 0xffff;
                 }
                 set
@@ Expand Down @@