Datacorder - implement basic manual tape block navigation (i.e. NextBlock, PrevBlock)

BizHawk.Emulation.Cores/Computers/SinclairSpectrum/Hardware/Datacorder/DatacorderDevice.cs

@@ -315,6 +315,66 @@ namespace BizHawk.Emulation.Cores.Computers.SinclairSpectrum
             _currentDataBlockIndex = 0;
         }
 
+        /// <summary>
+        /// Performs a block skip operation on the current tape
+        /// TRUE:   skip forward
+        /// FALSE:  skip backward
+        /// </summary>
+        /// <param name="skipForward"></param>
+        public void SkipBlock(bool skipForward)
+        {
+            int blockCount = _dataBlocks.Count;
+            int targetBlockId = _currentDataBlockIndex;
+
+            if (skipForward)
+            {
+                if (_currentDataBlockIndex == blockCount - 1)
+                {
+                    // last block, go back to beginning
+                    targetBlockId = 0;
+                }
+                else
+                {
+                    targetBlockId++;
+                }
+            }
+            else
+            {
+                if (_currentDataBlockIndex == 0)
+                {
+                    // already first block, goto last block
+                    targetBlockId = blockCount - 1;
+                }
+                else
+                {
+                    targetBlockId--;
+                }
+            }
+
+            var bl = _dataBlocks[targetBlockId];
+
+            StringBuilder sbd = new StringBuilder();
+            sbd.Append("(");
+            sbd.Append((targetBlockId + 1) + " of " + _dataBlocks.Count());
+            sbd.Append(") : ");
+            //sbd.Append("ID" + bl.BlockID.ToString("X2") + " - ");
+            sbd.Append(bl.BlockDescription);
+            if (bl.MetaData.Count > 0)
+            {
+                sbd.Append(" - ");
+                sbd.Append(bl.MetaData.First().Key + ": " + bl.MetaData.First().Value);
+                //sbd.Append("\n");
+                //sbd.Append(bl.MetaData.Skip(1).First().Key + ": " + bl.MetaData.Skip(1).First().Value);
+            }
+
+            if (skipForward)
+                _machine.Spectrum.OSD_TapeNextBlock(sbd.ToString());
+            else
+                _machine.Spectrum.OSD_TapePrevBlock(sbd.ToString());
+
+            CurrentDataBlockIndex = targetBlockId;
+        }
+
         /// <summary>
         /// Inserts a new tape and sets up the tape device accordingly
         /// </summary>

BizHawk.Emulation.Cores/Computers/SinclairSpectrum/Machine/SpectrumBase.Input.cs

@@ -15,12 +15,16 @@ namespace BizHawk.Emulation.Cores.Computers.SinclairSpectrum
         string Record = "Record Tape";
         string NextTape = "Insert Next Tape";
         string PrevTape = "Insert Previous Tape";
+        string NextBlock = "Next Tape Block";
+        string PrevBlock = "Prev Tape Block";
 
         bool pressed_Play = false;
         bool pressed_Stop = false;
         bool pressed_RTZ = false;
         bool pressed_NextTape = false;
         bool pressed_PrevTape = false;
+        bool pressed_NextBlock = false;
+        bool pressed_PrevBlock = false;
 
         public void PollInput()
         {
@@ -147,6 +151,30 @@ namespace BizHawk.Emulation.Cores.Computers.SinclairSpectrum
             }
             else
                 pressed_PrevTape = false;
+
+            if (Spectrum._controller.IsPressed(NextBlock))
+            {
+                if (!pressed_NextBlock)
+                {
+                    Spectrum.OSD_FireInputMessage(NextBlock);
+                    TapeDevice.SkipBlock(true);
+                    pressed_NextBlock = true;
+                }
+            }
+            else
+                pressed_NextBlock = false;
+
+            if (Spectrum._controller.IsPressed(PrevBlock))
+            {
+                if (!pressed_PrevBlock)
+                {
+                    Spectrum.OSD_FireInputMessage(PrevBlock);
+                    TapeDevice.SkipBlock(false);
+                    pressed_PrevBlock = true;
+                }
+            }
+            else
+                pressed_PrevBlock = false;
         }
 
         /// <summary>

BizHawk.Emulation.Cores/Computers/SinclairSpectrum/ZXSpectrum.Messaging.cs

@@ -178,6 +178,28 @@ namespace BizHawk.Emulation.Cores.Computers.SinclairSpectrum
             SendMessage(sb.ToString().TrimEnd('\n'), MessageCategory.Tape);
         }
 
+        /// <summary>
+        /// Tape message that is fired when user has manually skipped to the next block
+        /// </summary>
+        public void OSD_TapeNextBlock(string blockinfo)
+        {
+            StringBuilder sb = new StringBuilder();
+            sb.Append("Manual Skip Next " + blockinfo);
+
+            SendMessage(sb.ToString().TrimEnd('\n'), MessageCategory.Tape);
+        }
+
+        /// <summary>
+        /// Tape message that is fired when user has manually skipped to the next block
+        /// </summary>
+        public void OSD_TapePrevBlock(string blockinfo)
+        {
+            StringBuilder sb = new StringBuilder();
+            sb.Append("Manual Skip Prev " + blockinfo);
+
+            SendMessage(sb.ToString().TrimEnd('\n'), MessageCategory.Tape);
+        }
+
         #endregion
 
         /// <summary>