First attempt at a sampling GPIF waveform (untested!).

diff --git a/fx2lafw.c b/fx2lafw.c
index 0488cb7e83d6bf3d941b969d62af6880dbba7006..4505c138e7344e349e23a9a20ac9149a39c5f3e8 100644 (file)
--- a/fx2lafw.c
+++ b/fx2lafw.c
@@ -53,26 +53,66 @@ volatile bit got_sud;
 
 /* GPIF terminology: DP = decision point, NDP = non-decision-point */
 
-/* GPIF waveforms */
+/*
+ * GPIF waveforms.
+ *
+ * See section "10.3.4 State Instructions" in the TRM for details.
+ */
 static const BYTE wavedata[128] = {
        /* Waveform 0: */
 
-       /* TODO: This is just a dummy entry, fill with useful data. */
+       /*
+        * This is the basic algorithm implemented in our GPIF state machine:
+        *
+        * State 0: NDP: Sample the FIFO data bus.
+        * State 1: DP: If EP2 is full, go to state 7 (the IDLE state), i.e.,
+        *          end the current waveform. Otherwise, go to state 0 again,
+        *          i.e., sample data until EP2 is full.
+        * State 2: Unused.
+        * State 3: Unused.
+        * State 4: Unused.
+        * State 5: Unused.
+        * State 6: Unused.
+        */
 
        /* S0-S6: LENGTH/BRANCH */
-       0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+       /*
+        * For NDPs (LENGTH): Number of IFCLK cycles to stay in this state.
+        * For DPs (BRANCH): [7] ReExec, [5:3]: BRANCHON1, [2:0]: BRANCHON0.
+        *
+        * 0x01: Stay one IFCLK cycle in this state.
+        * 0x38: No Re-execution, BRANCHON1 = state 7, BRANCHON0 = state 0.
+        */
+       0x01, 0x38, 0x01, 0x01, 0x01, 0x01, 0x01,
        /* TRM says "reserved", but GPIF designer always puts a 0x07 here. */
        0x07,
+
        /* S0-S6: OPCODE */
-       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+       /*
+        * 0x02: NDP, sample the FIFO data bus.
+        * 0x01: DP, don't sample the FIFO data bus.
+        */
+       0x02, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,
        /* Reserved */
        0x00,
+
        /* S0-S6: OUTPUT */
+       /* Unused, we don't output anything, we only sample the pins. */
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        /* Reserved */
        0x00,
+
        /* S0-S6: LOGIC FUNCTION (not used for NDPs) */
-       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+       /*
+        * 0x36: LFUNC = "A AND B", A = FIFO flag, B = FIFO flag.
+        * The FIFO flag (FF == full flag, in our case) is configured via
+        * EP2GPIFFLGSEL.
+        *
+        * So: If the EP2 FIFO is full and the EP2 FIFO is full, go to
+        * the state specified by BRANCHON1 (state 7), otherwise BRANCHON0
+        * (state 0). See the LENGTH/BRANCH value above for details.
+        */
+       0x00, 0x36, 0x00, 0x00, 0x00, 0x00, 0x00,
        /* TRM says "reserved", but GPIF designer always puts a 0x3f here. */
        0x3f,
 
@@ -232,8 +272,8 @@ static void setup_endpoints(void)
        RESETFIFO(0x01)
        RESETFIFO(0x02)
 
-       /* Set the GPIF flag for EP2 to 'empty'. */
-       EP2GPIFFLGSEL = (0 << 1) | (1 << 1);
+       /* Set the GPIF flag for EP2 to 'full'. */
+       EP2GPIFFLGSEL = (1 << 1) | (0 << 1);
        SYNCDELAY();
 }