Add test, error too long jump tables.

fpgalib/dac.py

@@ -1198,12 +1198,12 @@ class DAC_Build15(DAC_Build8):
     SRAM_WRITE_PKT_LEN = 256
     SRAM_WRITE_DERPS = SRAM_LEN // SRAM_WRITE_PKT_LEN
 
-    JUMP_TABLE_LEN = 528
+    JUMP_TABLE_PACKET_LEN = 528
     NUM_COUNTERS = 4
     COUNTER_BYTES = 4
     IDLE_BITS = 15
     JUMP_TABLE_ENTRY_BYTES = 8
-    JUMP_TABLE_COUNT = (JUMP_TABLE_LEN - (NUM_COUNTERS * COUNTER_BYTES)
+    JUMP_TABLE_COUNT = (JUMP_TABLE_PACKET_LEN - (NUM_COUNTERS * COUNTER_BYTES)
                         ) / JUMP_TABLE_ENTRY_BYTES
     JT_FROM_ADDR_OFFSET = -2
     JT_END_ADDR_OFFSET = JT_FROM_ADDR_OFFSET - 1
@@ -1516,6 +1516,10 @@ def make_jump_table(cls, jt_entries, counters=None, start_address_ns=0):
         :rtype: jump_table.JumpTable
         """
 
+        if len(jt_entries) > cls.JUMP_TABLE_COUNT:
+            raise ValueError("Jump table too long: {} > {}"
+                             .format(len(jt_entries), cls.JUMP_TABLE_COUNT))
+
         # no two opcodes executed within JT_MIN_CLK_CYCLES_BETWEEN_OPCODES
         for k, jt_entry in enumerate(jt_entries):
             # first pass we check all increment cases
@@ -1542,7 +1546,8 @@ def make_jump_table(cls, jt_entries, counters=None, start_address_ns=0):
         return jump_table.JumpTable(
             start_addr=cls.convert_to_address(start_address_ns),
             jumps=jt_entries,
-            counters=counters
+            counters=counters,
+            PACKET_LEN=cls.JUMP_TABLE_PACKET_LEN,
         )
 
     @classmethod

fpgalib/jump_table.py

@@ -268,22 +268,26 @@ class JumpTable(object):
     TODO: make self.jumps a property with some checking on type and
         number.
     """
-    PACKET_LEN = 528
+
+    # TODO: Move these hardcoded FPGA values
     COUNTER_BITS = 32  # 32 bit register for counters
     COUNT_MAX = 2**COUNTER_BITS - 1
     NUM_COUNTERS = 4
 
-    def __init__(self, start_addr=None, jumps=None, counters=None):
+    def __init__(self, start_addr=None, jumps=None, counters=None,
+                 PACKET_LEN=528):
         """
 
         :param start_addr: start address
         :param list[JumpEntry] jumps: the jump table entries
         :param list[int] counters: the counter values
+        :param int PACKET_LEN: Number of packets in a JT write
         """
         self._startAddr = 0
         self.counters = self._initialize_counters(counters=counters)
         self.start_addr = start_addr
         self.jumps = jumps
+        self.PACKET_LEN = PACKET_LEN
 
     @classmethod
     def _initialize_counters(cls, counters=None):

fpgalib/test/test_dac.py

@@ -1,6 +1,7 @@
 """This is intended to test fpgalib/dac.py"""
 
 import pytest
+import numpy as np
 import fpgalib.dac as dac
 
 
@@ -99,5 +100,16 @@ def test_nop_nop_min_clk_ok(self):
             ('END', [400])
         ])
 
+    def test_too_many_entry(self):
+        entry_sep = self.dac.JT_MIN_CLK_CYCLES_BETWEEN_OPCODES * 4 * 2
+        from_addr = (entry_sep * np.arange(self.dac.JUMP_TABLE_COUNT + 1) +
+                     entry_sep)
+        entries = self.make_entries(
+            [('NOP', [k]) for k in from_addr] +
+            [('END', [from_addr[-1] + entry_sep])]
+        )
+        with pytest.raises(ValueError):
+            self.dac.make_jump_table(entries)
+
 if __name__ == '__main__':
     pytest.main(['-v', __file__])