diff options
| -rw-r--r-- | ffi.c | 20 | ||||
| -rw-r--r-- | ffi.h | 2 | ||||
| -rw-r--r-- | txr.1 | 18 |
3 files changed, 39 insertions, 1 deletions
@@ -74,6 +74,8 @@ val long_s, ulong_s; val double_s; val void_s; +val val_s; + val array_s, zarray_s, carray_s; val struct_s; @@ -82,6 +84,7 @@ val str_d_s, wstr_s, wstr_d_s, bstr_s, bstr_d_s; val buf_d_s; + val ptr_in_s, ptr_out_s, ptr_in_d_s, ptr_out_d_s, ptr_out_s_s, ptr_s; val closure_s; @@ -555,6 +558,16 @@ static val ffi_double_get(struct txr_ffi_type *tft, mem_t *src, val self) return flo(n); } +static void ffi_val_put(struct txr_ffi_type *tft, val v, mem_t *dst, val self) +{ + *coerce(val *, dst) = v; +} + +static val ffi_val_get(struct txr_ffi_type *tft, mem_t *src, val self) +{ + return *coerce(val *, src); +} + #if SIZEOF_WCHAR_T == SIZEOF_SHORT #define ffi_type_wchar ffi_type_ushort #elif SIZEOF_WCHAR_T == SIZEOF_INT @@ -1894,7 +1907,11 @@ static void ffi_init_types(void) alignof (double), &ffi_type_double, ffi_double_put, ffi_double_get)); - + ffi_typedef(val_s, make_ffi_type_builtin(val_s, t, + sizeof (val), + alignof (val), + &ffi_type_pointer, + ffi_val_put, ffi_val_get)); { val type = make_ffi_type_builtin(cptr_s, cptr_s, sizeof (mem_t *), alignof (mem_t *), @@ -2804,6 +2821,7 @@ void ffi_init(void) long_s = intern(lit("long"), user_package); ulong_s = intern(lit("ulong"), user_package); double_s = intern(lit("double"), user_package); + val_s = intern(lit("val"), user_package); void_s = intern(lit("void"), user_package); array_s = intern(lit("array"), user_package); zarray_s = intern(lit("zarray"), user_package); @@ -37,6 +37,8 @@ extern val long_s, ulong_s; extern val void_s; extern val double_s; +extern val val_s; + extern val array_s, zarray_s, carray_s; extern val struct_s; @@ -53374,6 +53374,24 @@ only \*(TL .code float type. +.ccIP @ val +The FFI +.code val +type denotes the machine representation of a Lisp value cell, which is +corresponds to a C pointer. Not all cell values are actually pointers, but +values that are heap objects, such as vectors and conses, are. +The +.code val +type transparently converts any Lisp object to a foreign pointer value +with no representation change at all; and performs the reverse conversion +from pointer to Lisp value. + +Note: this is utterly dangerous. Lisp values that aren't pointers must not +be dereferenced by foreign code. Foreign code must not generate Lisp pointer +values that aren't objects which came from a Lisp heap. +Interpreting a Lisp value in foreign code requires a correct decoding of +its type tag, and, if necessary, stripping the tag bits to recover a heap +pointer and interpreting the type code stored in the heap object. .ccIP @ cptr This type corresponds to a C pointer of any type, including a function pointer; \*(TX doesn't run on any exotic platforms in which there is a representational |