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modffi: Describe typecodes where they differ from used by struct module.

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Exact behavior of typecodes may be not yet enforced.
This commit is contained in:
Paul Sokolovsky 2014-04-21 23:17:12 +03:00
parent ca045d97b9
commit 88972b0d94
1 changed files with 18 additions and 2 deletions
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20
unix/modffi.c
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@ -12,6 +12,22 @@
#include "runtime.h"
#include "binary.h"
/*
* modffi uses character codes to encode a value type, based on "struct"
* module type codes, with some extensions and overridings.
*
* Extra/overridden typecodes:
* v - void, can be used only as return type
* P - const void*, pointer to read-only memory
* p - void*, meaning pointer to a writable memory (note that this
* clashes with struct's "p" as "Pascal string").
* s - as argument, the same as "p", as return value, causes string
* to be allocated and returned, instead of pointer value.
*
* Note: all constraint specified by typecode can be not enforced at this time,
* but may be later.
*/
typedef struct _mp_obj_opaque_t {
mp_obj_base_t base;
void *val;
@ -63,8 +79,8 @@ STATIC ffi_type *char2ffi_type(char c)
case 'L': return &ffi_type_ulong;
case 'f': return &ffi_type_float;
case 'd': return &ffi_type_double;
case 'p': // Deprecated - conflicts with struct module
case 'P':
case 'P': // const void*
case 'p': // void*
case 's': return &ffi_type_pointer;
case 'v': return &ffi_type_void;
default: return NULL;