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-rw-r--r--erts/example/matrix_nif.c70
1 files changed, 42 insertions, 28 deletions
diff --git a/erts/example/matrix_nif.c b/erts/example/matrix_nif.c
index 0e8ffdebcb..43f9526ae3 100644
--- a/erts/example/matrix_nif.c
+++ b/erts/example/matrix_nif.c
@@ -31,7 +31,19 @@ typedef struct
unsigned nrows;
unsigned ncols;
double* data;
-}Matrix;
+} Matrix;
+
+/*
+ * Use a union for pointer type conversion to avoid compiler warnings
+ * about strict-aliasing violations with gcc-4.1. gcc >= 4.2 does not
+ * emit the warning.
+ * TODO: Reconsider use of union once gcc-4.1 is obsolete?
+ */
+typedef union
+{
+ void* vp;
+ Matrix* p;
+} mx_t;
#define POS(MX, ROW, COL) ((MX)->data[(ROW)* (MX)->ncols + (COL)])
@@ -105,14 +117,14 @@ badarg:
static ERL_NIF_TERM pos(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
/* pos(Matrix, Row, Column) -> float() */
- Matrix* mx;
+ mx_t mx;
unsigned i, j;
- if (!enif_get_resource(env, argv[0], resource_type, (void**)&mx) ||
- !enif_get_uint(env, argv[1], &i) || (--i >= mx->nrows) ||
- !enif_get_uint(env, argv[2], &j) || (--j >= mx->ncols)) {
+ if (!enif_get_resource(env, argv[0], resource_type, &mx.vp) ||
+ !enif_get_uint(env, argv[1], &i) || (--i >= mx.p->nrows) ||
+ !enif_get_uint(env, argv[2], &j) || (--j >= mx.p->ncols)) {
return enif_make_badarg(env);
}
- return enif_make_double(env, POS(mx, i,j));
+ return enif_make_double(env, POS(mx.p, i,j));
}
static ERL_NIF_TERM add(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
@@ -120,37 +132,38 @@ static ERL_NIF_TERM add(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
/* add(Matrix_A, Matrix_B) -> Matrix_Sum */
unsigned i, j;
ERL_NIF_TERM ret;
- Matrix* mxA = NULL;
- Matrix* mxB = NULL;
- Matrix* mxS = NULL;
+ mx_t mxA, mxB, mxS;
+ mxA.p = NULL;
+ mxB.p = NULL;
+ mxS.p = NULL;
- if (!enif_get_resource(env, argv[0], resource_type, (void**)&mxA) ||
- !enif_get_resource(env, argv[1], resource_type, (void**)&mxB) ||
- mxA->nrows != mxB->nrows ||
- mxB->ncols != mxB->ncols) {
+ if (!enif_get_resource(env, argv[0], resource_type, &mxA.vp) ||
+ !enif_get_resource(env, argv[1], resource_type, &mxB.vp) ||
+ mxA.p->nrows != mxB.p->nrows ||
+ mxB.p->ncols != mxB.p->ncols) {
return enif_make_badarg(env);
}
- mxS = alloc_matrix(env, mxA->nrows, mxA->ncols);
- for (i = 0; i < mxA->nrows; i++) {
- for (j = 0; j < mxA->ncols; j++) {
- POS(mxS, i, j) = POS(mxA, i, j) + POS(mxB, i, j);
+ mxS.p = alloc_matrix(env, mxA.p->nrows, mxA.p->ncols);
+ for (i = 0; i < mxA.p->nrows; i++) {
+ for (j = 0; j < mxA.p->ncols; j++) {
+ POS(mxS.p, i, j) = POS(mxA.p, i, j) + POS(mxB.p, i, j);
}
}
- ret = enif_make_resource(env, mxS);
- enif_release_resource(mxS);
+ ret = enif_make_resource(env, mxS.p);
+ enif_release_resource(mxS.p);
return ret;
}
static ERL_NIF_TERM size_of(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
/* size(Matrix) -> {Nrows, Ncols} */
- Matrix* mx;
- if (!enif_get_resource(env, argv[0], resource_type, (void**)&mx)) {
+ mx_t mx;
+ if (!enif_get_resource(env, argv[0], resource_type, &mx.vp)) {
return enif_make_badarg(env);
}
- return enif_make_tuple2(env, enif_make_uint(env, mx->nrows),
- enif_make_uint(env, mx->ncols));
+ return enif_make_tuple2(env, enif_make_uint(env, mx.p->nrows),
+ enif_make_uint(env, mx.p->ncols));
}
static ERL_NIF_TERM to_term(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
@@ -158,16 +171,17 @@ static ERL_NIF_TERM to_term(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
/* to_term(Matrix) -> [[first row], [second row], ...,[last row]] */
unsigned i, j;
ERL_NIF_TERM res;
- Matrix* mx = NULL;
+ mx_t mx;
+ mx.p = NULL;
- if (!enif_get_resource(env, argv[0], resource_type, (void**)&mx)) {
+ if (!enif_get_resource(env, argv[0], resource_type, &mx.vp)) {
return enif_make_badarg(env);
}
res = enif_make_list(env, 0);
- for (i = mx->nrows; i-- > 0; ) {
+ for (i = mx.p->nrows; i-- > 0; ) {
ERL_NIF_TERM row = enif_make_list(env, 0);
- for (j = mx->ncols; j-- > 0; ) {
- row = enif_make_list_cell(env, enif_make_double(env, POS(mx,i,j)),
+ for (j = mx.p->ncols; j-- > 0; ) {
+ row = enif_make_list_cell(env, enif_make_double(env, POS(mx.p,i,j)),
row);
}
res = enif_make_list_cell(env, row, res);