Coldfire uC5282 Question

[Eric Norum]

On Mar 30, 2010, at 11:32 AM, Thomas Dörfler wrote:

> Eric, Joel,
> 
> Joels listing really shows the opcode 0x51ca
> 
> I have looked it up in an of M68k manual. The problem I see is bit 3,
> because this is even an illegal coding for 68k:
> Bit 5-3 in the opcode hold the "Adressing MODE" field, and the coding
> 001 in it is undefined (would select an adress register instead of data
> register as destination).

Nope.  It's actually a completely different instruction (DBCC).

But in any case, that's illegal for a ColdFire.

> 
> So -> compiler problem. The compiler should never generate this code.
> Even the assembler shouldn't.
> 
> What does "objdump" say to that opcode?
> 
> wkr,
> Thomas.
> 
> 
> 
> On 30.03.2010 20:14, Eric Norum wrote:
>> That's the standard 'SCC' command (Set Condition Code) -- In everything from the 68000 on up.
>> 
>>> From the programmer's guide:
>> 
>> Attributes:   Size = (Byte)
>> 
>> Description:	The specified condition code is tested. If the condition is true, the bits at the effective address are all set to one (i.e., $FF). Otherwise, the bits at the effective address are set to zeros (i.e., $00).
>> 
>> 
>> 
>> 
>> So,  'SF' would be 'Set On False' -- i.e. set never.   Another way to  'clear byte' I guess.
>> 
>> Kind of a corner case for the SCC instruction, but the emulator really should handle it!
>> 
>> On Mar 30, 2010, at 10:48 AM, Joel Sherrill wrote:
>> 
>>> Hi,
>>> 
>>> I am running gcc testsuite on the qemu uC5282
>>> simulator.  I am getting a number of failures
>>> where qemu says an illegal instruction was
>>> encountered.  Can a coldfire person out there
>>> tell me whether this is qemu not supporting
>>> a valid coldfire instruction or this instruction
>>> should not be generated by gcc with the -mcpu=5282
>>> option
>>> 
>>> [joel at rtbf64b gcc]$ m68k-rtems4.10-objdump -da zero-struct-2.x7 | grep -i "51 ca"
>>> [joel at rtbf64b gcc]$ m68k-rtems4.10-objdump -da zero-struct-2.x7 | grep -i "5186c"
>>>  5186c:    51ca               sf %d2
>>> 
>>> 
>>> $ uC5282 -i zero-struct-2.x7
>>> /users/joel/qemu-coverage/install/bin/qemu-system-m68k is /users/joel/qemu-coverage/install/bin/qemu-system-m68k
>>> qemu: fatal: Illegal instruction: 51ca @ 0005186c
>>> D0 = 00000000   A0 = 00063b98   F0 = 0000000000000000 (           0)
>>> D1 = 00000034   A1 = 00063186   F1 = 0000000000000000 (           0)
>>> D2 = 00000000   A2 = 00063b98   F2 = 0000000000000000 (           0)
>>> D3 = 000615e6   A3 = 00000000   F3 = 0000000000000000 (           0)
>>> D4 = 00000034   A4 = 00000000   F4 = 0000000000000000 (           0)
>>> D5 = 00000000   A5 = 00000000   F5 = 0000000000000000 (           0)
>>> D6 = 00000000   A6 = 2000ffcc   F6 = 0000000000000000 (           0)
>>> D7 = 00000000   A7 = 2000ffa0   F7 = 0000000000000000 (           0)
>>> PC = 00051864   SR = 2700 ----- FPRESULT =            0
>>> [joel at rtbf64b gcc]$ uC5282 zero-struct-2.x7^C
>>> 
>>> Thanks.
>>> 
>>> -- 
>>> Joel Sherrill, Ph.D.             Director of Research&  Development
>>> joel.sherrill at OARcorp.com        On-Line Applications Research
>>> Ask me about RTEMS: a free RTOS  Huntsville AL 35805
>>>  Support Available             (256) 722-9985
>>> 
>>> 
>>> _______________________________________________
>>> rtems-users mailing list
>>> rtems-users at rtems.org
>>> http://www.rtems.org/mailman/listinfo/rtems-users
>> 
> 
> 
> -- 
> 
> --------------------------------------------
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-- 
Eric Norum
wenorum at lbl.gov