For the typemap you need to add typemap entries that map your types to the same as the other int types, eg. in typemap:

gf2_u8     T_UV
gf2_u16    T_UV
gf2_u32    T_UV
gf2_s8     T_IV
gf2_s16    T_IV
gf2_s32    T_IV
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ExtUtils::MakeMaker should pick up the type map automatically when you run Makefile.PL.

As to whether those types are the correct types, one possibility is stdint.h, which requires a C99 compiler/libc, but in most cases, if the C compiler has 8 and 16 bit int types, char and short will be them.

Unfortunately perl doesn't probe for stdint.h, so it's something you'd need to probe for yourself.

For 32-bit, long might be 64-bit*, so in the absence of inttypes.h you could use limits.h:

#include <limits.h>

#if USHRT_MAX > 0x80000000
typedef unsigned short gf2_u32;
#elif UINT_MAX > 0x80000000
typedef unsigned gf2_u32;
#else
typedef unsigned long gf2_u32;
#endif
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* According to the standard, they could all be 128-bit, but most likely char is 8 bit if the compiler has an 8-bit type, and unless the compiler has stdint.h, short will be the 16 bit type if there is one.