topic push and pop CCR register on stack in 8-bit Microcontrollers

push and pop CCR register on stack

grzegorzK — Thu, 15 Jan 2015 13:35:57 GMT

I use MC9S08DZ60. I would like to get functionality to push and pop CCR register on/from stack.

Something similar as quoted macros below (from PE) but CCR saved on stacked variable, not global variable as in example from PE

#define SaveStatusReg() { asm PSHA; asm TPA; asm SEI; asm STA CCR_reg; asm PULA; }

#define RestoreStatusReg() { asm PSHA; asm LDA CCR_reg; asm TAP; asm PULA; }

where CCR_reg is global variable, I would like to use auto variable located on stack,

e.g:

#define SaveStatusReg() volatile byte CCR_stack; asm PSHA; asm TPA; asm SEI; asm XXX CCR_stack; asm PULA;

Could someone help me?

Best Regards

/Greg

Re: push and pop CCR register on stack

tonyp — Thu, 15 Jan 2015 13:46:24 GMT

ASM8 uses the PSHCC and PULCC internal macros which correspond to this:

[from ASM8 manual http://www.aspisys.com/asm8.pdf]:

PSHCC (PUSH CCR)

-----------------------------

PSHA

TPA

STA 2,SP

TAP

PULA

PULCC (PULL CCR)

----------------------------

PSHA

LDA 2,SP

TAP

PULA

AIS #1

PSHCC is careful to not change the CCR bits on push.

Hope this helps.

Re: push and pop CCR register on stack

grzegorzK — Fri, 16 Jan 2015 10:01:35 GMT

thank you for your replay.

I do not understand what means "internal", internal of what? I should mention that I use CW10.6 envornoment for build target. I am looking macro for use in C module as in Processor Expert example.

Regards

/GReg

Re: push and pop CCR register on stack

kef2 — Fri, 16 Jan 2015 12:25:42 GMT

#define SaveStatusReg() char CCR_stack; asm PSHA; asm TPA; asm SEI; asm STA CCR_reg; asm PULA;

#define RestoreStatusReg() { asm PSHA; asm LDA CCR_reg; asm TAP; asm PULA; }

Should work, provided SaveStatusReg() in { } block comes immediately after variables. Like

void foo()

{

int a;

char b;

// only variables here

SaveStatusReg();

...

}

void foo()

{

int a;

a++;

a--;

{

char inner_block_vars;

SaveStatusReg();

....

RestoreStatusReg();

}

...

}

Re: push and pop CCR register on stack

grzegorzK — Fri, 16 Jan 2015 15:13:56 GMT

Yes, works (if somne want use it, be cerfull with typo in name of auto variable)

Thank You.