3d2e39a · Idris-dev · git.iko.soy

docs/reference/ffi.rst+15−2

compare with master

unifiedsplit

@@ -217,8 +217,21 @@ global variable with the following name. The type must be just ``IO Ptr``.

217 errno : IO Ptr

218 errno = foreign FFI_C "&errno" (IO Ptr)

219

220+If the foreign name is prefixed by a ``#``, the name is pasted in literally. This is

221+useful to access constants that are preprocessor definitions (like ``INT_MAX``).

222+

223+..code-block:: idris

224+ %include C "limits.h"

225+

226+ -- access the preprocessor definition INT_MAX

227+ intMax : IO Int

228+ intMax = foreign FFI_C "#INT_MAX" (IO Int)

229+

230+ main : IO ()

231+ main = print !intMax

232+

220−For more complicated interactions with C (such as reading and setting fields of a C struct), there is

233+For more complicated interactions with C (such as reading and setting fields

221−a module CFFI available in the contrib package.

234+of a C struct), there is a module CFFI available in the contrib package.

222

235

223FFI implementation

236FFI implementation

224------------------

237------------------

src/IRTS/CodegenC.hs+3

@@ -314,6 +314,9 @@ bcc i (TOPBASE n) = indent i ++ "TOPBASE(" ++ show n ++ ");\n"

314bcc i (BASETOP n) = indent i ++ "BASETOP(" ++ show n ++ ");\n"

315bcc i STOREOLD = indent i ++ "STOREOLD;\n"

316bcc i (OP l fn args) = indent i ++ doOp (creg l ++ " = ") fn args ++ ";\n"

317+bcc i (FOREIGNCALL l rty (FStr ('#':name)) [])

318+ = indent i ++

319+ c_irts (toFType rty) (creg l ++ " = ") name ++ ";\n"

317bcc i (FOREIGNCALL l rty (FStr fn@('&':name)) [])

320bcc i (FOREIGNCALL l rty (FStr fn@('&':name)) [])

318 = indent i ++

321 = indent i ++

319 c_irts (toFType rty) (creg l ++ " = ") fn ++ ";\n"

322 c_irts (toFType rty) (creg l ++ " = ") fn ++ ";\n"

test/ffi007/expected+1

@@ -7,3 +7,4 @@ After calling callback

7I'm dynamic 3

86

97

10+3

test/ffi007/ffi007.h+2

@@ -1,6 +1,8 @@

1#include <stdint.h>

2typedef int (*callback)(int);

3

4+#define THREE 3

5+

4int32_t testvar = 887;

6int32_t testvar = 887;

5

7

6void test_ffi(int (*cb)(int));

8void test_ffi(int (*cb)(int));

test/ffi007/ffi007.idr+6−1

@@ -42,6 +42,10 @@ test8 : IO ()

42test8 = foreign FFI_C "test_mulpar" (CFnPtr (Int -> Int -> ()) -> IO ())

43 (MkCFnPtr adder)

44

45+

46+test9 : IO Int

47+test9 = foreign FFI_C "#THREE" (IO Int)

48+

45main : IO ()

49main : IO ()

46main = do

50main = do

47 test

51 test

@@ -55,4 +59,5 @@ main = do

55 i <- test7 fptr 3

59 i <- test7 fptr 3

56 printLn i

60 printLn i

57 test8

61 test8

62+ printLn !test9

58− pure ()

63+ pure ()