Superdrive: implement track seeking.

devices/floppy/floppyimg.cpp

@@ -169,6 +169,15 @@ int RawFloppyImg::calc_phys_params()
             this->num_sectors = size_to_params[i].num_sectors;
             this->num_sides   = size_to_params[i].num_sides;
             this->density     = size_to_params[i].density;
+
+            // fake format byte for GCR disks
+            if (!this->rec_method) {
+                this->format_byte = (this->num_sides == 2) ? 0x22 : 0x2;
+            } else {
+                // For MFM disks this byte indicates sector size in blocks
+                this->format_byte = 2;
+            }
+            break;
         }
     }
 

devices/floppy/floppyimg.h

@@ -56,6 +56,7 @@ public:
     int get_number_of_sides()  { return this->num_sides;   };
     int get_sectors_per_side() { return this->num_sectors; };
     int get_rec_density()      { return this->density;     };
+    uint8_t get_format_byte()  { return this->format_byte; };
 
 protected:
     std::string img_path;
@@ -67,6 +68,7 @@ protected:
     int         num_sides;
     int         num_sectors;
     int         density;
+    uint8_t     format_byte; // GCR format byte from sector header
 };
 
 /** Converter for raw floppy images. */

devices/floppy/superdrive.cpp

@@ -40,7 +40,7 @@ MacSuperDrive::MacSuperDrive()
     this->eject_latch = 0; // eject latch is off
     this->drive_mode  = RecMethod::MFM; // assume MFM mode by default
     this->motor_stat  = 0; // spindle motor is off
-    this->head_pos    = 0; // current head position
+    this->cur_track   = 0; // current head position
     this->is_ready    = 0; // drive not ready
 }
 
@@ -56,10 +56,10 @@ void MacSuperDrive::command(uint8_t addr, uint8_t value)
         break;
     case CommandAddr::Do_Step:
         if (!value) {
-            this->head_pos += this->step_dir;
-            if (this->head_pos < 0)
-                this->head_pos = 0;
-            this->track_zero = this->head_pos == 0;
+            this->cur_track += this->step_dir;
+            if (this->cur_track < 0)
+                this->cur_track = 0;
+            this->track_zero = this->cur_track == 0;
         }
         break;
     case CommandAddr::Motor_On_Off:
@@ -101,6 +101,9 @@ uint8_t MacSuperDrive::status(uint8_t addr)
         return this->motor_stat ^ 1; // reverse logic
     case StatusAddr::Eject_Latch:
         return this->eject_latch;
+    case StatusAddr::Select_Head_0:
+        this->cur_head = 0;
+        return 1; // not sure what should be returned here
     case StatusAddr::MFM_Support:
         return 1; // Superdrive does support MFM encoding scheme
     case StatusAddr::Double_Sided:
@@ -113,6 +116,9 @@ uint8_t MacSuperDrive::status(uint8_t addr)
         return this->wr_protect ^ 1; // reverse logic
     case StatusAddr::Track_Zero:
         return this->track_zero ^ 1; // reverse logic
+    case StatusAddr::Select_Head_1:
+        this->cur_head = 1;
+        return 1; // not sure what should be returned here
     case StatusAddr::Drive_Mode:
         return this->drive_mode;
     case StatusAddr::Drive_Ready:
@@ -157,10 +163,11 @@ int MacSuperDrive::insert_disk(std::string& img_path)
 
 void MacSuperDrive::set_disk_phys_params()
 {
-    this->rec_method = this->img_conv->get_disk_rec_method();
-    this->num_tracks = this->img_conv->get_number_of_tracks();
-    this->num_sides  = this->img_conv->get_number_of_sides();
-    this->media_kind = this->img_conv->get_rec_density();
+    this->rec_method  = this->img_conv->get_disk_rec_method();
+    this->num_tracks  = this->img_conv->get_number_of_tracks();
+    this->num_sides   = this->img_conv->get_number_of_sides();
+    this->media_kind  = this->img_conv->get_rec_density();
+    this->format_byte = this->img_conv->get_format_byte();
 
     switch_drive_mode(this->rec_method);
 }
@@ -200,3 +207,33 @@ void MacSuperDrive::switch_drive_mode(int mode)
         this->drive_mode = RecMethod::MFM;
     }
 }
+
+double MacSuperDrive::get_current_track_delay()
+{
+    return (1.0f / (this->rpm_per_track[this->cur_track] / 60));
+}
+
+double MacSuperDrive::get_sector_delay()
+{
+    return this->get_current_track_delay() / this->sectors_per_track[this->cur_track];
+}
+
+void MacSuperDrive::init_track_search(int pos)
+{
+    if (pos == -1) {
+        // pick random sector number
+        this->cur_sector = this->sectors_per_track[this->cur_track] / 2;
+    } else {
+        this->cur_sector = pos;
+    }
+}
+
+SectorHdr MacSuperDrive::next_sector_header()
+{
+    return SectorHdr {
+        this->cur_track,
+        this->cur_head,
+        this->cur_sector++,
+        this->format_byte
+    };
+}

devices/floppy/superdrive.h

@@ -38,12 +38,14 @@ enum StatusAddr : uint8_t {
     Step_Status   = 1,
     Motor_Status  = 2,
     Eject_Latch   = 3,
+    Select_Head_0 = 4,
     MFM_Support   = 5,
     Double_Sided  = 6,
     Drive_Exists  = 7,
     Disk_In_Drive = 8,
     Write_Protect = 9,
     Track_Zero    = 0xA,
+    Select_Head_1 = 0xC,
     Drive_Mode    = 0xD,
     Drive_Ready   = 0xE,
     Media_Kind    = 0xF
@@ -70,6 +72,13 @@ enum RecMethod : int {
     MFM = 1
 };
 
+typedef struct SectorHdr {
+    int track;
+    int side;
+    int sector;
+    int format;
+} SectorHdr;
+
 class MacSuperDrive : public HWComponent {
 public:
     MacSuperDrive();
@@ -78,6 +87,10 @@ public:
     void command(uint8_t addr, uint8_t value);
     uint8_t status(uint8_t addr);
     int insert_disk(std::string& img_path);
+    double get_current_track_delay();
+    double get_sector_delay();
+    void init_track_search(int pos);
+    SectorHdr next_sector_header();
 
 protected:
     void set_disk_phys_params();
@@ -91,11 +104,14 @@ private:
     uint8_t is_ready;
     uint8_t track_zero;  // 1 - if head is at track zero
     int     step_dir;    // step direction -1/+1
-    int     head_pos;    // track number the head is currently at
+    int     cur_track;   // track number the head is currently at
+    int     cur_head;    // current head number: 1 - upper, 0 - lower
+    int     cur_sector;  // current sector number
 
     // physical parameters of the currently inserted disk
     uint8_t media_kind;
     uint8_t wr_protect;
+    uint8_t format_byte;
     int     rec_method;
     int     num_tracks;
     int     num_sides;