Add big integer to double conversion

Refactor term_conv_to_float in order to use intn_to_double function.
Also make sure in opcodesswitch that term_conv_to_float() returns a
finite value.

Signed-off-by: Davide Bettio <davide@uninstall.it>

Author: bettio

src/libAtomVM/intn.h

@@ -70,6 +70,8 @@ char *intn_to_string(const intn_digit_t *num, size_t len, intn_integer_sign_t nu
 int intn_parse(
     const char buf[], size_t buf_len, int base, intn_digit_t *out, intn_integer_sign_t *out_sign);
 
+double intn_to_double(const intn_digit_t *num, size_t len, intn_integer_sign_t sign);
+
 static inline void intn_copy(
     const intn_digit_t *num, size_t num_len, intn_digit_t *out, size_t extend_to)
 {

src/libAtomVM/opcodesswitch.h

@@ -6108,7 +6108,11 @@ HOT_FUNC int scheduler_entry_point(GlobalContext *glb)
                     if (UNLIKELY(!term_is_number(src_value))) {
                         RAISE_ERROR(BADARITH_ATOM);
                     }
-                    ctx->fr[freg] = term_conv_to_float(src_value);
+                    avm_float_t converted = term_conv_to_float(src_value);
+                    if (UNLIKELY(!isfinite(converted))) {
+                        RAISE_ERROR(BADARITH_ATOM);
+                    }
+                    ctx->fr[freg] = converted;
                 #endif
 
                 #ifdef IMPL_CODE_LOADER

src/libAtomVM/term.c

@@ -895,3 +895,34 @@ term term_get_map_assoc(term map, term key, GlobalContext *glb)
     }
     return term_get_map_value(map, pos);
 }
+
+avm_float_t term_conv_to_float(term t)
+{
+    if (term_is_float(t)) {
+        return term_to_float(t);
+    } else if (term_is_integer(t)) {
+        return term_to_int(t);
+    } else if (term_is_boxed_integer(t)) {
+        size_t boxed_size = term_boxed_size(t);
+        switch (boxed_size) {
+            case 0:
+                UNREACHABLE();
+            case 1:
+                return term_unbox_int(t);
+#if BOXED_TERMS_REQUIRED_FOR_INT64 == 2
+            case 2:
+                return term_unbox_int64(t);
+#endif
+            default: {
+                const intn_digit_t *num = (intn_digit_t *) term_intn_data(t);
+                size_t digits_per_term = (sizeof(term) / sizeof(intn_digit_t));
+                size_t len = boxed_size * digits_per_term;
+                term_integer_sign_t t_sign = term_boxed_integer_sign(t);
+
+                return intn_to_double(num, len, (intn_integer_sign_t) t_sign);
+            }
+        }
+    } else {
+        UNREACHABLE();
+    }
+}

src/libAtomVM/term.h

@@ -1566,15 +1566,6 @@ static inline avm_float_t term_to_float(term t)
     return boxed_float->f;
 }
 
-static inline avm_float_t term_conv_to_float(term t)
-{
-    if (term_is_any_integer(t)) {
-        return term_maybe_unbox_int64(t);
-    } else {
-        return term_to_float(t);
-    }
-}
-
 static inline bool term_is_number(term t)
 {
     return term_is_any_integer(t) || term_is_float(t);
@@ -1624,6 +1615,8 @@ int term_fprint(FILE *fd, term t, const GlobalContext *global);
  */
 int term_snprint(char *buf, size_t size, term t, const GlobalContext *global);
 
+avm_float_t term_conv_to_float(term t);
+
 /**
  * @brief Checks if a term is a string (i.e., a list of characters)
  *

tests/erlang_tests/bigint.erl

@@ -27,6 +27,7 @@
     sort/1,
     twice/1,
     fact/1,
+    divtrunc/2,
     the_out_of_order_list/0,
     the_ordered_list/0,
     get_machine_atom/0,
@@ -46,7 +47,8 @@
 start() ->
     test_mul() +
         parse_bigint() +
-        test_cmp().
+        test_cmp() +
+        conv_to_float().
 
 test_mul() ->
     Expected_INT64_MIN = ?MODULE:pow(-2, 63),
@@ -514,6 +516,31 @@ sort([Pivot | T]) ->
 sort([]) ->
     [].
 
+conv_to_float() ->
+    Int0 = ?MODULE:id(erlang:binary_to_integer(?MODULE:id(<<"1000000000000000000">>), 16)),
+    Int1 = ?MODULE:id(
+        erlang:binary_to_integer(?MODULE:id(<<"CAFECAFE1234000000000000000000">>), 16)
+    ),
+    Int2 = ?MODULE:id(
+        erlang:binary_to_integer(?MODULE:id(<<"-CAFECAFE1234000000000000000000">>), 16)
+    ),
+    Num1 = ?MODULE:mul(?MODULE:id(Int1), ?MODULE:id(erlang:binary_to_float(?MODULE:id(<<"1.0">>)))),
+    Num2 = ?MODULE:mul(?MODULE:id(Int2), ?MODULE:id(erlang:binary_to_float(?MODULE:id(<<"1.0">>)))),
+    Num3 = ?MODULE:id(Int1) * ?MODULE:id(erlang:binary_to_float(?MODULE:id(<<"2.0">>))),
+    true =
+        erlang:binary_to_integer(?MODULE:id(<<"CAFECAFE1234">>), 16) =:=
+            ?MODULE:divtrunc(?MODULE:id(Num1), Int0),
+    true =
+        erlang:binary_to_integer(?MODULE:id(<<"-CAFECAFE1234">>), 16) =:=
+            ?MODULE:divtrunc(?MODULE:id(Num2), Int0),
+    true =
+        erlang:binary_to_integer(?MODULE:id(<<"195FD95FC2468">>), 16) =:=
+            ?MODULE:divtrunc(?MODULE:id(Num3), Int0),
+    0.
+
+divtrunc(X, Y) ->
+    erlang:trunc(X / Y).
+
 id(X) ->
     X.