Help needed: small piece of assembler code for IRAF

[Andreas Schwab]

As IRAF is a 40-year old package, there was already some assembler that
.text
.globl _zsvjmp_
JMPBUF = 4
STATUS = 8
_zsvjmp_: |# CALL ZSVJMP (JMPBUF, STATUS)
jmp _setjmp |# let setjmp do the rest.
However, just including this does not work because assembler syntax
changed [3].

Registers need to be prefixed with %, and assembler labels for C symbols
do not have a _ prefix.

[Adam Sampson]

Hi Ole,

I created a small repository [4] that contains the assembler I
collected so far as well as two test programs.

The code you've written looks OK -- the only problem is that in
glibc, sigsetjmp is a macro which calls the real function __sigsetjmp:
https://sourceware.org/git/?p=glibc.git;a=blob;f=setjmp/setjmp.h;hb=HEAD#l72

So you need "jra __sigsetjmp" (as you've done on other architectures),
rather than "jra sigsetjmp". With that change, your tests work on an
emulated m68k machine:

$ git diff
diff --git a/zsvjmp-m68k.s b/zsvjmp-m68k.s
index 3b12e5d..43ca08c 100644
--- a/zsvjmp-m68k.s
+++ b/zsvjmp-m68k.s
@@ -12,7 +12,7 @@ zsvjmp_:
move.l %a1,(%a0)+
clr.l 8(%sp)
move.l %a0,4(%sp)
- jra sigsetjmp
+ jra __sigsetjmp

.size zsvjmp_, .-zsvjmp_
.section .note.GNU-stack,"",@progbits

$ make ARCH=m68k test
gfortran -ff2c -g -c -o jmptest.o jmptest.f
gcc -g -c -o zdojmp.o zdojmp.c
as -o zsvjmp-m68k.o zsvjmp-m68k.s
ar cr libzsvjmp.a zdojmp.o zsvjmp-m68k.o
gfortran -o jmptest jmptest.o -L. -lzsvjmp
gcc -g -c -o zzdebug.o zzdebug.c
gcc -g -g -o zzdebug zzdebug.o -L. -lzsvjmp
./zzdebug
Status = 0, step = 0
Calling zdojmp
Status = 1, step = 1
All OK
./jmptest
Status = 0 step = 0
Calling zdojmp
Status = 4294967296 step = 1
All OK
STOP 0

Thanks,