Hi,

This patch fixes a problem I ran across while working on an internal 
port. Incorrect opcodes and masks were sometimes being generated for the 
short insns of variable length ISAs because of two problems in 
-opcode-slots:

1) The test of bit positions against the insn-length was off by one. 
Thjs could lead to incorrect opcode bits being generated.

2) While the 'compute' function correctly generated zeroes for the extra 
bits when computing 'opcode', it was also generating zeroes for these 
bits when computing 'opcode-mask', thus rendering these bits irrelevent. 
This could lead to the generation of numerous unreachable cases in the 
generated decoder switch.

The patch corrects the comparison of bit position against the 
insn-length and also allows the caller of 'compute' to specify the 
default bit value which should be generated bits beyond the length of a 
short insn. This allows 0 to be specified when computing 'opcode' and 1 
to be specified when computing opcode-mask. The patch also changes some 
of the logit calls to print values in hex which is more appropriate when 
examining bitmasks

This patch corrects the problem encountered with my internal port. I 
know of no other port which is affected by this bug. I have tested it 
against frv and xstormy16 and verified no changes to the generated decoders.

OK to commit?

Dave