Did your posted code compile for you? Cos I get this lot:

junk.c
junk.xs(21) : error C2275: 'SV' : illegal use of this type as an expre
+ssion
        C:\Perl64\lib\CORE\perl.h(2400) : see declaration of 'SV'
junk.xs(21) : error C2065: 'sp' : undeclared identifier
junk.xs(21) : error C2100: illegal indirection
junk.xs(23) : error C2143: syntax error : missing ';' before 'type'
junk.xs(30) : error C2065: 'sp' : undeclared identifier
junk.xs(30) : error C2113: '-' : pointer can only be subtracted from a
+nother pointer
junk.xs(33) : error C2065: 'sp' : undeclared identifier
junk.xs(33) : warning C4047: '<' : 'SV **' differs in levels of indire
+ction from 'int'
junk.xs(33) : error C2065: 'sp' : undeclared identifier
junk.xs(33) : error C2065: 'sp' : undeclared identifier
junk.xs(33) : warning C4047: 'function' : 'SV **' differs in levels of
+ indirection from 'int'
junk.xs(33) : warning C4024: 'Perl_stack_grow' : different types for f
+ormal and actual parameter 2
junk.xs(33) : error C2065: 'sp' : undeclared identifier
junk.xs(33) : warning C4047: 'function' : 'SV **' differs in levels of
+ indirection from 'int'
junk.xs(33) : warning C4024: 'Perl_stack_grow' : different types for f
+ormal and actual parameter 3
junk.xs(33) : warning C4047: '=' : 'int' differs in levels of indirect
+ion from 'SV **'
junk.xs(33) : error C2065: 'sp' : undeclared identifier
junk.xs(33) : error C2100: illegal indirection
junk.xs(33) : warning C4047: '=' : 'int' differs in levels of indirect
+ion from 'SV *'
junk.xs(33) : error C2106: '=' : left operand must be l-value
junk.xs(36) : error C2065: 'sp' : undeclared identifier
junk.xs(36) : warning C4047: '=' : 'SV **' differs in levels of indire
+ction from 'int'
junk.xs(40) : error C2065: 'count' : undeclared identifier
junk.xs(44) : error C2065: 'sp' : undeclared identifier
junk.xs(44) : warning C4047: '=' : 'int' differs in levels of indirect
+ion from 'SV **'
junk.xs(49) : error C2065: 'count' : undeclared identifier
junk.xs(52) : error C2065: 'sp' : undeclared identifier
junk.xs(52) : error C2100: illegal indirection
junk.xs(52) : warning C4047: '=' : 'SV *' differs in levels of indirec
+tion from 'int'
junk.xs(52) : warning C4244: '=' : conversion from 'IV' to 'int', poss
+ible loss of data
junk.xs(56) : error C2065: 'sp' : undeclared identifier
junk.xs(56) : warning C4047: '=' : 'SV **' differs in levels of indire
+ction from 'int'
NMAKE : fatal error U1077: '"c:\Program Files (x86)\Microsoft Visual S
+tudio 9.0\VC\Bin\amd64\cl.EXE"' : return code '0x2'
Stop.

[download]

Maybe your compiler allows you to take liberties with the C rule that declarations must come before executable statements?

Anyway, I've always felt that placing dSP; and similar XS declarations at the very top of the function is probably best. I also had to move int rv; above the printf. That fixed up all the errors and warnings except for:

    rv = POPi;
junk.xs(51) : warning C4244: '=' : conversion from 'IV' to 'int', poss
+ible loss of data

[download]

which is because I'm using 64-bit.

It runs clean showing no signs of memory leaks.

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.

In reply to Re^3: When to (and not to) use sv_2mortal() by BrowserUk
in thread When to (and not to) use sv_2mortal() by davido

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