Re^4: How get PV address?

Thanks, I set return type to UV, it works and I can call it back and forth in C:

use strict;
use warnings;
use Devel::Peek;

my $dd = "hello world\n";
Dump $dd;
my $ee = cc($dd);
printf("the dd string address is %x \n", cc($dd));
dd($ee);
use Inline Config => BUILD_NOISY => 1,
                                       CLEAN_AFTER_BUILD => 0;
use Inline 'C' => <<'CODE';

int dd(UV x){

                printf("string is %s \n", (char*)x);
                return 0;
}
UV cc(SV* a){
return SvPVX(a);
}
CODE
###############output###########
andy@andyhome:~/one-off$ perl abe.pl
SV = PV(0x56386170b050) at 0x56386172f008
  REFCNT = 1
  FLAGS = (POK,IsCOW,pPOK)
  PV = 0x5638617addf0 "hello world\n"\0
  CUR = 12
  LEN = 14
  COW_REFCNT = 1
the dd string address is 5638617addf0
string is hello world
[download]

I pass it back to perl, But I got little confused: in typemap, both unsigned int and UV refer to T_UV and in OUTPUT it does convert to UV:

int             T_IV
unsigned        T_UV
unsigned int    T_UV
UV              T_UV
T_UV
     sv_setuv($arg, (UV)$var);
[download]

why seems perl neglect typemap file but use config?

Platform:
    osname=linux
    osvers=4.15.0-52-generic
    archname=x86_64-linux
    uname='linux andyhome 4.15.0-52-generic #56-ubuntu smp tue jun 4 2
+2:49:08 utc 2019 x86_64 x86_64 x86_64 gnulinux '
    config_args='-de -Dprefix=/home/andy/perl5/perlbrew/perls/perl-5.3
+0.0 -Aeval:scriptdir=/home/andy/perl5/perlbrew/perls/perl-5.30.0/bin'
    hint=recommended
    useposix=true
    d_sigaction=define
    useithreads=undef
    usemultiplicity=undef
    use64bitint=define
    use64bitall=define
    uselongdouble=undef
    usemymalloc=n
    default_inc_excludes_dot=define
    bincompat5005=undef
  Compiler:
    cc='cc'
    ccflags ='-fwrapv -fno-strict-aliasing -pipe -fstack-protector-str
+ong -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64'
    optimize='-O2'
    cppflags='-fwrapv -fno-strict-aliasing -pipe -fstack-protector-str
+ong -I/usr/local/include'
    ccversion=''
    gccversion='7.4.0'
    gccosandvers=''
    intsize=4
    longsize=8
    ptrsize=8
    doublesize=8
    byteorder=12345678
[download]

Please enlighten me.

I am trying to improve my English skills, if you see a mistake please feel free to reply or /msg me a correction

Comment on Re^4: How get PV address? Select or Download Code

Replies are listed 'Best First'.
Re^5: How get PV address? by dave_the_m (Monsignor) on Aug 06, 2019 at 07:13 UTC
You are using a typemap to create an SV to return to perl. That SV is being assigned an integer value. The only types of integer values that SVs can have are IVs and UVs. Hence a plain integer gets upgraded to an IV/UV before being assigned to the SV. Dave.	[reply]
Re^6: How get PV address? by xiaoyafeng (Deacon) on Aug 06, 2019 at 08:31 UTC
Hence a plain integer gets upgraded to an IV/UV before being assigned to the SV. That's what I thought before, but as above, in typemap, unsigned int also use sv_setnv function. Does it mean sv_setnv function wouldn't upgrade an IV to UV silently if it get a unsigned integer? I am trying to improve my English skills, if you see a mistake please feel free to reply or /msg me a correction	[reply]
Re^7: How get PV address? by dave_the_m (Monsignor) on Aug 06, 2019 at 10:03 UTC
I don't understand why you are now talking about sv_setnv(): this doesn't appear in the typemap you showed above. The standard typemap for outputting integer values will do either sv_setiv($arg, (IV)$var) or sv_setuv($arg, (UV)$var) depending on whether the integer type is signed or not. The IV or UV types are usually defined as being the largest integer type that the compiler supports: they're large enough to hold a pointer, and often larger than a plain int (8 bytes versus 4 bytes). Dave.	[reply]
Re^8: How get PV address? by xiaoyafeng (Deacon) on Aug 06, 2019 at 12:55 UTC