Initialising a stack for a new thread

[Timothy Baldwin]

void thread();

...

static uint8_t stack[40];
*(uint16_t *)(stack + sizeof(stack) - 2) = uint16_t(&thread);
stack_pointer = stack + sizeof(stack) - 21;

When the new thread was switched to the program would restart. The address is on the right place on the stack. The stack is large enough. Weird answer later.

[Joe Woodbury]

Shouldn't this be under coding horrors?

Anyone who thinks he has a better idea of what's good for people than people do is a swine. - P.J. O'Rourke

[Timothy Baldwin]

It would better fit under CPU design horrors. It turned out that I was writing the address in the wrong byte order. This otherwise little-endian system has a big-endian stack!

[geoffs]

What cpu is this that the code was written for?

[Timothy Baldwin]

Atmel AVR, specifically a ATMega168 micro-controler.

[geoffs]

Thanks, Tim. I like to keep my brain aware of these little oddball processors. I mostly work with embedded stuff on TI DSPs or Microblaze soft-processors in FPGAs.

[Stephen Hewitt]

Timothy Baldwin wrote:

This otherwise little-endian system has a big-endian stack!

That seems more than a little bizarre!

Steve

[peterchen]

Depends on who wrote it. "Subtle bugs" = mine "Coding Horrors" = everyone elses But anyway, with the low traffic it would be ok to merge the two boards. "Subtle Horrors", maybe?

We are a big screwed up dysfunctional psychotic happy family - some more screwed up, others more happy, but everybody's psychotic joint venture definition of CP
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[Gary R Wheeler]

Coding Bugs: It's What's For Dinner!™

Software Zen: delete this;
Fold With Us![^]