Changeset 3c17057 in avrstuff

Timestamp:

Jan 15, 2012, 10:44:43 AM (12 years ago)

Author:

Adrien Destugues <pulkomandy@…>

Branches:

main

Children:

89e680d

Parents:

e69146a

Message:

Fix bugs related to minimal-size blocks. Loading a standard game works !

git-svn-id: ​svn://pulkomandy.tk/avrstuff@54 c6672c3c-f6b6-47f9-9001-1fd6b12fecbe

File:

• V-USB_Dev/firmwares/CrO2/main.c (modified) (6 diffs)

V-USB_Dev/firmwares/CrO2/main.c

@@ -14 +14 @@
 static uint16_t writePos;
 static uint16_t blksz;
+static uint8_t cksum;
 
 static uint16_t readPos;
@@ -41 +42 @@
                 ioblock[i] = 1;
         }
-        ioblock[i++] = 0x3C;
-        ioblock[i++] = 0x5A;
-
-        // HEAD block
-        ioblock[i++] = 0x0;
-        ioblock[i++] = 0x10;
-
-        int j = i;
-        ioblock[i++] = 'C';
-        ioblock[i++] = 'r';
-        ioblock[i++] = 'O';
-        ioblock[i++] = '2';
-        ioblock[i++] = ' ';
-        ioblock[i++] = ' ';
-        ioblock[i++] = ' ';
-        ioblock[i++] = ' ';
-        ioblock[i++] = 'B';
-        ioblock[i++] = 'A';
-        ioblock[i++] = 'S';
-        ioblock[i++] = 0;
-        ioblock[i++] = 0;
-        ioblock[i++] = 0;
-        uint8_t s = 0;
-        for (;j<i;j++) s -= ioblock[j];
-        ioblock[i++] = s;
-
+        ioblock[16] = 0x3C;
+        ioblock[17] = 0x5A;
 
         // Setup TIMER 1 for MFM pulses generation
@@ -89 +66 @@
 
 
+static inline void startGen()
+{
+        TCCR1A &= ~(1<<COM1A1); // Toggle output on compare match
+        TCCR1B |= (1<<CS10);    // Enable timer clock (prescaler = 1)
+}
+
+
 uint8_t usbFunctionSetup(uint8_t data[8]) {
         usbRequest_t *rq = (void *)data;
@@ -108 +92 @@
                                 /* SEND DATA (USB > TAPE) */
                                 /* Get ready, actual data will come in usbFunctionWrite */
-                                // TODO store type of MO5 block + size in ioblock
-                                writePos = 0;
-                                blksz = rq->wLength.word;
-                                return USB_NO_MSG; // Call usbFunctionWrite to send the data
+
+                                // store type of MO5 block + size in ioblock
+                                writePos = 20; // Leave space for Sync header, block type, and block size.
+                                ioblock[18] = rq->wValue.word;
+                                ioblock[19] = rq->wLength.word + 2; // Add blktype and cksum to data length
+                                blksz = rq->wLength.word + 21;
+                                cksum = 0;
+                                if (rq->wLength.word == 0)
+                                {
+                                        // No data in this block - start generating now !
+                                        ioblock[20] = 0; // checksum
+                                        startGen();
+                                } else {
+                                        return USB_NO_MSG; // Call usbFunctionWrite to send the data
+                                }
                         }
         }
@@ -122 +117 @@
         for (int i = 0; i < len; i++)
         {
-                // TODO leave place for sync header and block type+size
-//              ioblock[writePos] = data[i];
+                ioblock[writePos] = data[i];
+                cksum -= data[i];
                 writePos++;
         }
 
-        // TODO compute checksum as we go
+        ioblock[writePos] = cksum;
 
-        if (writePos >= blksz)
+        if (writePos >= blksz - 1)
         {
                 // start generating
-                TCCR1A &= ~(1<<COM1A1);
-                TCCR1B |= (1<<CS10);
-                blksz = 35;
+                startGen();
                 return 1;
         } else {
@@ -155 +148 @@
                 if (readPos > blksz)
                 {
-                        // Make sure output is high
+                        // Make sure output is high step 1: match action = force high level
                         TCCR1A |= (1<<COM1A1);
+
                         // Stop generating (and interrupts)
                         TCCR1B &= ~(1<<CS10);
                         readPos = 0;
+
+                        // make sure output is high step 2 : force a match.
                         TCCR1A |= (1 << FOC1A);
                 }