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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 19:33:14 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 19:33:14 +0000 |
commit | 36d22d82aa202bb199967e9512281e9a53db42c9 (patch) | |
tree | 105e8c98ddea1c1e4784a60a5a6410fa416be2de /js/src/ctypes/libffi/man/ffi_call.3 | |
parent | Initial commit. (diff) | |
download | firefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.tar.xz firefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.zip |
Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'js/src/ctypes/libffi/man/ffi_call.3')
-rw-r--r-- | js/src/ctypes/libffi/man/ffi_call.3 | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/js/src/ctypes/libffi/man/ffi_call.3 b/js/src/ctypes/libffi/man/ffi_call.3 new file mode 100644 index 0000000000..5351513f90 --- /dev/null +++ b/js/src/ctypes/libffi/man/ffi_call.3 @@ -0,0 +1,103 @@ +.Dd February 15, 2008 +.Dt ffi_call 3 +.Sh NAME +.Nm ffi_call +.Nd Invoke a foreign function. +.Sh SYNOPSIS +.In ffi.h +.Ft void +.Fo ffi_call +.Fa "ffi_cif *cif" +.Fa "void (*fn)(void)" +.Fa "void *rvalue" +.Fa "void **avalue" +.Fc +.Sh DESCRIPTION +The +.Nm ffi_call +function provides a simple mechanism for invoking a function without +requiring knowledge of the function's interface at compile time. +.Fa fn +is called with the values retrieved from the pointers in the +.Fa avalue +array. The return value from +.Fa fn +is placed in storage pointed to by +.Fa rvalue . +.Fa cif +contains information describing the data types, sizes and alignments of the +arguments to and return value from +.Fa fn , +and must be initialized with +.Nm ffi_prep_cif +before it is used with +.Nm ffi_call . +.Pp +.Fa rvalue +must point to storage that is sizeof(ffi_arg) or larger for non-floating point +types. For smaller-sized return value types, the +.Nm ffi_arg +or +.Nm ffi_sarg +integral type must be used to hold +the return value. +.Sh EXAMPLES +.Bd -literal +#include <ffi.h> +#include <stdio.h> + +unsigned char +foo(unsigned int, float); + +int +main(int argc, const char **argv) +{ + ffi_cif cif; + ffi_type *arg_types[2]; + void *arg_values[2]; + ffi_status status; + + // Because the return value from foo() is smaller than sizeof(long), it + // must be passed as ffi_arg or ffi_sarg. + ffi_arg result; + + // Specify the data type of each argument. Available types are defined + // in <ffi/ffi.h>. + arg_types[0] = &ffi_type_uint; + arg_types[1] = &ffi_type_float; + + // Prepare the ffi_cif structure. + if ((status = ffi_prep_cif(&cif, FFI_DEFAULT_ABI, + 2, &ffi_type_uint8, arg_types)) != FFI_OK) + { + // Handle the ffi_status error. + } + + // Specify the values of each argument. + unsigned int arg1 = 42; + float arg2 = 5.1; + + arg_values[0] = &arg1; + arg_values[1] = &arg2; + + // Invoke the function. + ffi_call(&cif, FFI_FN(foo), &result, arg_values); + + // The ffi_arg 'result' now contains the unsigned char returned from foo(), + // which can be accessed by a typecast. + printf("result is %hhu", (unsigned char)result); + + return 0; +} + +// The target function. +unsigned char +foo(unsigned int x, float y) +{ + unsigned char result = x - y; + return result; +} +.Ed +.Sh SEE ALSO +.Xr ffi 3 , +.Xr ffi_prep_cif 3 |