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Hello I wonder if someone could give me a hint about the most efficient way to allocate variables in data flash on a DSP56800E using Codewarrior. The goal is to have a larger chunk (e.g. a struct) of some rarely changing parameters remain persistent in data flash where they would be read-only in normal use, and not get overwritten at reboot. Declaring them as CONST looks like it would have them re-initialized by the start-up code ... Many thanks! Robert |
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allocating variables in data rom
Started by ●May 23, 2004
Reply by ●May 26, 20042004-05-26
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Hi Robert We have regions of FLASH that we only write to with explicit "config" commands. We access it with pointers-to-structs, or pointers-to-arrays-of-words, so the linker cmd file never locates variables there. However, we usually copy from that area into RAM variables at boot time and after re-configuring, so we're not space-efficient. This is unnecessary. Rick Corey -----Original Message----- From: Robert Imhoff [mailto:] Sent: Sunday, May 23, 2004 2:44 AM To: Subject: [motoroladsp] allocating variables in data rom Hello I wonder if someone could give me a hint about the most efficient way to allocate variables in data flash on a DSP56800E using Codewarrior. The goal is to have a larger chunk (e.g. a struct) of some rarely changing parameters remain persistent in data flash where they would be read-only in normal use, and not get overwritten at reboot. Declaring them as CONST looks like it would have them re-initialized by the start-up code ... Many thanks! Robert _____________________________________ Note: If you do a simple "reply" with your email client, only the author of this message will receive your answer. You need to do a "reply all" if you want your answer to be distributed to the entire group. _____________________________________ About this discussion group: To Join: To Post: To Leave: Archives: http://www.yahoogroups.com/group/motoroladsp More Groups: http://www.dsprelated.com/groups.php3 Yahoo! Groups Links |
Reply by ●May 26, 20042004-05-26
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Hi Robert, I am using CW6.0 and the array that I declared as const is properly allocated in X Flash memory (starting in X:0x1800 for the 56F826). For example: const int a[6]={1,2,3,4,5,6}; int main(void) { .... This is the disassembly code: *** INITIALIZED DATA (.rodata) *** 0x00000000: 01 00 02 00 03 00 04 00 05 00 06 00 '............' (Note that it is displaying the values as little, but this was fixed to show big-endian in version 6.1) Make sure that in Settings/Code Generation/M56800 Processor you selected "Write constant data to .rodata section". Best regards, Fabio Estevam -----Original Message----- From: Robert Imhoff [mailto:] Sent: domingo, 23 de maio de 2004 03:44 To: Subject: [motoroladsp] allocating variables in data rom Hello I wonder if someone could give me a hint about the most efficient way to allocate variables in data flash on a DSP56800E using Codewarrior. The goal is to have a larger chunk (e.g. a struct) of some rarely changing parameters remain persistent in data flash where they would be read-only in normal use, and not get overwritten at reboot. Declaring them as CONST looks like it would have them re-initialized by the start-up code ... Many thanks! Robert _____________________________________ Note: If you do a simple "reply" with your email client, only the author of this message will receive your answer. You need to do a "reply all" if you want your answer to be distributed to the entire group. _____________________________________ About this discussion group: To Join: To Post: To Leave: Archives: http://www.yahoogroups.com/group/motoroladsp More Groups: http://www.dsprelated.com/groups.php3 Yahoo! Groups Links |
