[Coco] Second eyes needed for C to ASM ABI strangeness.

[Joel Rees]

So Walter, have you got anywhere with this?

2019年10月23日(水) 15:39 lost <lost at l-w.ca>:

> Looks like you may have an issue with value sizes and maybe endianness.
> You haven't included enough information though. We need to know what you
> declared the functions as. Particularly the return types. If you haven't
> declared the asm one, its return type will default to int which is probably
> half the size of long. Depending on endianness and calling convention that
> could mean the high order bits are saved in the variable instead of the low
> order bits. The other cases may only be working properly accidentally due
> to an accident of register allocation or something.
> -------- Original message --------From: Walter Zambotti <
> zambotti at iinet.net.au> Date: 2019-10-23  00:13  (GMT-07:00) To: 'CoCoList
> for Color Computer Enthusiasts' <coco at maltedmedia.com> Subject: [Coco]
> Second eyes needed for C to ASM ABI strangeness. In following code where I
> call two shift functions. One written in C and theother in assembly (both
> functions not shown): long val, val1, val2;short shft;   printf("%ld
> %ld\n", shift(val, shft), shiftasm(val, shft));  val1 = shift(val, shft);
> val2 = shiftasm(val, shft);  printf("%ld %ld\n", val1, val2); where val = 1
> and shft = 1; outputs the following: 2 22 0 If I change: val2 =
> shiftasm(val, shft); to: val2 = 0 + shiftasm(val, shft); Then the output
> is: 2 22 2 Which is now correct. It appears I cannot directly assign the
> output of my asm function directlyto a variable without having some sort of
> temporary expression such as "0 +"or passed to another function such as
> printf. So I'm not sure what the C to asm ABI should be! Any ideas? Walter
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