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Per Westermark
01/20/12 02:52
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Sweden


 
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#185582 - So exactly what was the disagreement???
Responding to: Per Westermark's previous message
I'm still waiting with interest for someone to pick up the ball and tell why they don't agree with my previous post.

Some architectures will be better to handle one C code construct while another architecture will better handle other constructs.

With a 8051 chip, we can have a single C statement that sets/clears a processor pin, and it will end up as an optimal match in assembler. Same when we assign values to the SFR to configure a peripherial.

Another processor may dislike immediate addresses but love register-indirect pointers with additional offset. So they will get optimum code when everything is accessed using a pointer to a structure mapping the individual SFR for the peripherial. The pointer access has zero cost, and the offsets are so small that they can be embedded directly in the access instruction.

But to be able to know what maps well and what maps badly, we just have to be able to read assembler output. Even if not able to write code, we must be able to see the amount of instructions, and recognize which instructions are expensive (such as giving memory access/pipeline stalls or a multi-clockcycle divide) and which large set of assembler instructions that could be reduced to just one or two if the original C code had described the problem in another way potentially removing a C language standard forced requirement for the compiler.

List of 49 messages in thread
TopicAuthorDate
interfacing with 93c66      Anil Kumar      01/14/12 01:04      
   Interfacing AT93CXXX Serial EEPROMs with AT89LP MCUs      Jan Waclawek      01/14/12 04:20      
      Direct Links      Michael Karas      01/14/12 11:04      
   interfacing ith93c66      Anil Kumar      01/16/12 03:09      
      Better Learn Both      Michael Karas      01/16/12 18:01      
      How about the 8051 code library?      Neil Kurzman      01/16/12 23:30      
         interfacing with 93c66      Anil Kumar      01/18/12 22:51      
            An exercise for the reader      David Prentice      01/19/12 01:20      
               interfacing with 93c66      Anil Kumar      01/19/12 22:59      
      Then you need to learn...      Robert Revens      01/19/12 05:34      
         I disgaree        David Prentice      01/19/12 06:25      
            cheap fatty sausage      Erik Malund      01/19/12 07:04      
               Understanding the mapping important      Per Westermark      01/19/12 07:43      
                  out of context      Erik Malund      01/19/12 09:13      
                  So exactly what was the disagreement???      Per Westermark      01/20/12 02:52      
                     I agree with you      David Prentice      01/20/12 03:55      
                        Don't simplify to believe it's about fastest speed      Per Westermark      01/20/12 05:27      
                        again      Erik Malund      01/20/12 07:48      
                     true      Erik Malund      01/20/12 07:42      
               Are you serious?      David Prentice      01/19/12 08:15      
                  also out of context      Erik Malund      01/19/12 09:16      
               Missing the point!      Andy Neil      01/19/12 12:19      
                  the full monte      Erik Malund      01/19/12 12:37      
   interfacing with 93c66      Anil Kumar      01/26/12 21:56      
      And your work      Per Westermark      01/27/12 02:46      
      plz check it      Andy Neil      01/27/12 06:58      
      ,sometimes you have to be VERY specific      Erik Malund      01/27/12 07:31      
      wrong strategy and many errors      Stefan KAnev      01/30/12 04:12      
   interfacing with 93c66      Anil Kumar      01/28/12 03:16      
      why do you resist using external ram?      Erik Malund      01/28/12 08:58      
         interfacing with 93c66      Anil Kumar      01/29/12 02:21      
            Payed support not good enough?        Per Westermark      01/29/12 03:18      
               interfacing with 93c66      Anil Kumar      01/29/12 22:29      
                  Any Specific Reason for using...      Maunik Choksi      01/29/12 23:09      
                     interfacing with 93c66      Anil Kumar      01/29/12 23:33      
                        please explain      Andy Neil      01/30/12 14:39      
                        It is advisable to use alternate available....      Maunik Choksi      01/30/12 22:37      
                           interfacing with 93c66      Anil Kumar      01/31/12 22:06      
                              Can you elaborate it ?      Maunik Choksi      01/31/12 22:44      
                                 interfacing with 93c66      Anil Kumar      01/31/12 22:51      
                                    You give me your email-id      Maunik Choksi      01/31/12 22:53      
                                       email id      Anil Kumar      01/31/12 22:57      
                                          Ok      Maunik Choksi      01/31/12 22:58      
                  Wrong - you are just not responding to on-topic questions      Per Westermark      01/30/12 03:00      
                  you've got plenty of suggestions      Erik Malund      01/30/12 06:53      
                     Off-topic but Siemens/seconds...      Per Westermark      01/30/12 08:04      
                     funny result      Erik Malund      02/02/12 09:20      
                        Output      Per Westermark      02/02/12 15:14      
   still waiting      Erik Malund      02/01/12 06:49      

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