'I' cannot represent function return value

[LinJian1982]

EXPORT_WASM_API_WITH_SIG(wasm_get_microsecond, "()I"),

issue log as below:
[00:06:43:847 - C22A6280]: failed to check signature '()I' and resolve pointer params for import function (env wasm_get_microsecond)

[xujuntwt95329]

Hi, how did you declare the wasm_get_microsecond function in your wasm application?

This log means the function signature mismatched between the wasm module and runtime

[LinJian1982]

@xujuntwt95329
uint64 wasm_get_microsecond(wasm_exec_env_t exec_env)

[xujuntwt95329]

@LinJian1982 Hi, uint64 wasm_get_microsecond(wasm_exec_env_t exec_env) is the signature of your native API, I wonder how did you declare the signature of this function in wasm application?

Did you write something like this to declare the function prototype in your application code?

extern uint64_t wasm_get_microsecond();

[LinJian1982]

@xujuntwt95329
Hi,

I do have following declared in my app header file. I have the same issue for both host(x86-64) and arm-32 platform.

#include "bh_platform.h"

#ifdef __cplusplus
extern "C" {
#endif

/* A time value that is accurate to the nearest
   microsecond but also has a range of years.  */
struct timeval
{
    uint32 tv_sec;		/* Seconds.  */
    uint32 tv_usec;	    /* Microseconds.  */
};

uint64 api_get_microsecond();

[xujuntwt95329]

@LinJian1982
Hi, which bh_platform.h are you using? If you are using core/shared/utils/bh_platform.h, then that is for native, and the actual bitwidth of uint64 is decided by the native OS, it may be incompatible with wasm's type. e.g. the long int is treated as 64bit integer on 64bit Ubuntu OS, but it is treated as 32bit integer in wasm.

You can change the definition to

unsigned long long int 
api_get_microsecond();

I think this could fix the problem.

BTW, thanks to your issue, I found that the uint64_t definition in our libc-builtin-sysroot also use the wrong bit width, I'll fix it soon and then you can use uint64_t in your application file if you use the libc-builtin-sysroot.

[xujuntwt95329]

I've submitted a PR #898 to fix the issue in libc-builtin-sysroot

[LinJian1982]

@xujuntwt95329
I see there is no definition for uint64 in app sdk, so I defined it as "unsigned long". But looks like the compiler think it is a 32bit platform, so "unsigned long" is 32 bit.
So I changed the uint64 definition to "unsigned long long", then the issue resolved.

[LinJian1982]

@xujuntwt95329

I just see your reply. Accidently, looks like I followed your proposal. 👍

Jian