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I have noticed a weird thing. My startup code looks like this: #pragma CODE_SEG FLSH_ROM #pragma NO_FRAME void a_reset(void) { unsigned int *int_ee_location; // write to mapping registers once asm { clra staa INITRG ; control regs at $0000-$03ff nop ldaa #0x21 staa INITRM ; RAM at $2000-$3FFF nop ldaa #0x09 staa INITEE ; interal EEPROM at $0800-$0fff nop } asm { /* redundant, unless call ever made to reset() */ orcc #0xd0 disable interrupts, disable stop inst., disable XIRQ lds #0x03ffe ; initialize stack }; The first instruction the compliler generates is a PSHD. The stack pointer is not yet initialized. Where does this instruction come from and how can I get rid of it? Thanks, B.K. |
Metrowerks HC12 Compiler
Started by ●January 28, 2005
Reply by ●January 28, 20052005-01-28
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Just a guess:
Unsigned int *int_ee_location; Is being allocated for you on the stack via the push rather than the less efficient method of adding to stack for one variable location. To get rid of this, use a global of the variable, or a static for *int_ee_location. This of course means dedicating a piece of RAM for this one routine called once, but you could always use a temp location that could be re-used at the sake of maintainability. Other things I have done in the past is my main function would have parameters rather than void, and chew a few bytes of default/random stack location. -Mark W _____ From: bkohan_2000 [mailto:] Sent: Friday, January 28, 2005 11:49 AM To: Subject: [68HC12] Metrowerks HC12 Compiler I have noticed a weird thing. My startup code looks like this: #pragma CODE_SEG FLSH_ROM #pragma NO_FRAME void a_reset(void) { unsigned int *int_ee_location; // write to mapping registers once asm { clra staa INITRG ; control regs at $0000-$03ff nop ldaa #0x21 staa INITRM ; RAM at $2000-$3FFF nop ldaa #0x09 staa INITEE ; interal EEPROM at $0800-$0fff nop } asm { /* redundant, unless call ever made to reset() */ orcc #0xd0 disable interrupts, disable stop inst., disable XIRQ lds #0x03ffe ; initialize stack }; The first instruction the compliler generates is a PSHD. The stack pointer is not yet initialized. Where does this instruction come from and how can I get rid of it? Thanks, B.K. _____ > Terms of Service. |
Reply by ●January 28, 20052005-01-28
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The pshd comes from > unsigned int *int_ee_location; As the compiler allocates space on stack. I do not see your full code below, but you can only use local vars if you have a stack. You may make it global or static local if you really need it that time. Or set the stack pointer earlier (separate the functionality with local variable into a separate function you call after the stack is initialized). Erich > -----Original Message----- > From: bkohan_2000 [mailto:] > Sent: Freitag, 28. Januar 2005 17:49 > To: > Subject: [68HC12] Metrowerks HC12 Compiler > > > I have noticed a weird thing. My startup code looks like this: > > #pragma CODE_SEG FLSH_ROM > #pragma NO_FRAME > void a_reset(void) > { > unsigned int *int_ee_location; > > // write to mapping registers once > asm { > clra > staa INITRG ; control regs at $0000-$03ff > nop > ldaa #0x21 > staa INITRM ; RAM at $2000-$3FFF > nop > ldaa #0x09 > staa INITEE ; interal EEPROM at $0800-$0fff > nop > } > > asm { /* redundant, unless call ever made to reset() */ > orcc #0xd0 disable interrupts, disable stop inst., disable > XIRQ > lds #0x03ffe ; initialize stack > }; > > The first instruction the compliler generates is a PSHD. The stack > pointer is not yet initialized. Where does this instruction come > from and how can I get rid of it? > > Thanks, > > B.K. > > Yahoo! Groups Links |
