Implement the new ceil/1 and floor/1 guard BIFs

Implement as ceil/1 and floor/1 as new guard BIFs (essentially part of
Erlang language). They are guard BIFs because trunc/1 is a guard
BIF. It would be strange to have trunc/1 as a part of the language, but
not ceil/1 and floor/1.

6 files changed, 183 insertions, 19 deletions

diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml
index d0a3a77e43..18a7a5b777 100644
--- a/erts/doc/src/erlang.xml
+++ b/erts/doc/src/erlang.xml
@@ -718,6 +718,19 @@ Z = erlang:adler32_combine(X,Y,iolist_size(Data2)).</code>
     </func>
 
     <func>
+      <name name="ceil" arity="1"/>
+      <fsummary>Returns the smallest integer not less than the argument</fsummary>
+      <desc>
+        <p>Returns the smallest integer not less than
+	<c><anno>Number</anno></c>.
+        For example:</p>
+        <pre>
+> <input>ceil(5.5).</input>
+6</pre>
+        <p>Allowed in guard tests.</p>
+      </desc>
+    </func>
+    <func>
       <name name="check_old_code" arity="1"/>
       <fsummary>Check if a module has old code.</fsummary>
       <desc>
@@ -1465,6 +1478,20 @@ true</pre>
     </func>
 
     <func>
+      <name name="floor" arity="1"/>
+      <fsummary>Returns the largest integer not greater than the argument</fsummary>
+      <desc>
+        <p>Returns the largest integer not greater than
+	<c><anno>Number</anno></c>.
+        For example:</p>
+        <pre>
+> <input>floor(-10.5).</input>
+-11</pre>
+        <p>Allowed in guard tests.</p>
+      </desc>
+    </func>
+
+    <func>
       <name name="fun_info" arity="1"/>
       <fsummary>Information about a fun.</fsummary>
       <desc>
diff --git a/erts/emulator/beam/bif.tab b/erts/emulator/beam/bif.tab
index 7a35c02934..67eae35dec 100644
--- a/erts/emulator/beam/bif.tab
+++ b/erts/emulator/beam/bif.tab
@@ -659,6 +659,13 @@ bif erlang:has_prepared_code_on_load/1
 bif maps:take/2
 
 #
+# New in 20.0
+#
+
+gcbif erlang:floor/1
+gcbif erlang:ceil/1
+
+#
 # Obsolete
 #
 
diff --git a/erts/emulator/beam/erl_bif_guard.c b/erts/emulator/beam/erl_bif_guard.c
index b42d2dc28b..458315f293 100644
--- a/erts/emulator/beam/erl_bif_guard.c
+++ b/erts/emulator/beam/erl_bif_guard.c
@@ -141,6 +141,39 @@ BIF_RETTYPE trunc_1(BIF_ALIST_1)
     BIF_RET(res);
 }
 
+BIF_RETTYPE floor_1(BIF_ALIST_1)
+{
+    Eterm res;
+    FloatDef f;
+
+    if (is_not_float(BIF_ARG_1)) {
+	if (is_integer(BIF_ARG_1))
+	    BIF_RET(BIF_ARG_1);
+	BIF_ERROR(BIF_P, BADARG);
+    }
+    GET_DOUBLE(BIF_ARG_1, f);
+    res = double_to_integer(BIF_P, floor(f.fd));
+    BIF_RET(res);
+}
+
+BIF_RETTYPE ceil_1(BIF_ALIST_1)
+{
+    Eterm res;
+    FloatDef f;
+
+    /* check arg */
+    if (is_not_float(BIF_ARG_1)) {
+	if (is_integer(BIF_ARG_1))
+	    BIF_RET(BIF_ARG_1);
+	BIF_ERROR(BIF_P, BADARG);
+    }
+    /* get the float */
+    GET_DOUBLE(BIF_ARG_1, f);
+
+    res = double_to_integer(BIF_P, ceil(f.fd));
+    BIF_RET(res);
+}
+
 BIF_RETTYPE round_1(BIF_ALIST_1)
 {
     Eterm res;
@@ -621,6 +654,38 @@ Eterm erts_gc_trunc_1(Process* p, Eterm* reg, Uint live)
 				reg, live);
 }
 
+Eterm erts_gc_floor_1(Process* p, Eterm* reg, Uint live)
+{
+    Eterm arg;
+    FloatDef f;
+
+    arg = reg[live];
+    if (is_not_float(arg)) {
+	if (is_integer(arg))  {
+	    return arg;
+	}
+	BIF_ERROR(p, BADARG);
+    }
+    GET_DOUBLE(arg, f);
+    return gc_double_to_integer(p, floor(f.fd), reg, live);
+}
+
+Eterm erts_gc_ceil_1(Process* p, Eterm* reg, Uint live)
+{
+    Eterm arg;
+    FloatDef f;
+
+    arg = reg[live];
+    if (is_not_float(arg)) {
+	if (is_integer(arg))  {
+	    return arg;
+	}
+	BIF_ERROR(p, BADARG);
+    }
+    GET_DOUBLE(arg, f);
+    return gc_double_to_integer(p, ceil(f.fd), reg, live);
+}
+
 static Eterm
 gc_double_to_integer(Process* p, double x, Eterm* reg, Uint live)
 {
diff --git a/erts/emulator/test/num_bif_SUITE.erl b/erts/emulator/test/num_bif_SUITE.erl
index d1c9648017..1a1ab0e5e0 100644
--- a/erts/emulator/test/num_bif_SUITE.erl
+++ b/erts/emulator/test/num_bif_SUITE.erl
@@ -32,6 +32,8 @@
 %%	list_to_integer/1
 %%	round/1
 %%	trunc/1
+%%      floor/1
+%%      ceil/1
 %%	integer_to_binary/1
 %%	integer_to_binary/2
 %%	binary_to_integer/1
@@ -41,7 +43,7 @@
 	 t_float_to_string/1, t_integer_to_string/1,
 	 t_string_to_integer/1, t_list_to_integer_edge_cases/1,
 	 t_string_to_float_safe/1, t_string_to_float_risky/1,
-	 t_round/1, t_trunc/1
+	 t_round/1, t_trunc_and_friends/1
      ]).
 
 suite() -> [{ct_hooks,[ts_install_cth]}].
@@ -49,7 +51,7 @@ suite() -> [{ct_hooks,[ts_install_cth]}].
 all() ->
     [t_abs, t_float, t_float_to_string, t_integer_to_string,
      {group, t_string_to_float}, t_string_to_integer, t_round,
-     t_trunc, t_list_to_integer_edge_cases].
+     t_trunc_and_friends, t_list_to_integer_edge_cases].
 
 groups() ->
     [{t_string_to_float, [],
@@ -295,30 +297,78 @@ t_round(Config) when is_list(Config) ->
     -4294967297 = -round(id(4294967296.9)),
     ok.
 
-t_trunc(Config) when is_list(Config) ->
-    0 = trunc(id(0.0)),
-    5 = trunc(id(5.3333)),
-    -10 = trunc(id(-10.978987)),
+%% Test trunc/1, floor/1, ceil/1, and round/1.
+t_trunc_and_friends(_Config) ->
+    MinusZero = 0.0 / (-1.0),
+    0 = trunc_and_friends(MinusZero),
+    0 = trunc_and_friends(0.0),
+    5 = trunc_and_friends(5.3333),
+    -10 = trunc_and_friends(-10.978987),
 
-    % The largest smallnum, converted to float (OTP-3722):
+    %% The largest smallnum, converted to float (OTP-3722):
     X = id((1 bsl 27) - 1),
-    F = id(X + 0.0),
+    F = X + 0.0,
     io:format("X = ~p/~w/~w, F = ~p/~w/~w, trunc(F) = ~p/~w/~w~n",
 	      [X, X, binary_to_list(term_to_binary(X)),
 	       F, F, binary_to_list(term_to_binary(F)),
-	       trunc(F), trunc(F), binary_to_list(term_to_binary(trunc(F)))]),
-    X = trunc(F),
-    X = trunc(F+1)-1,
-    X = trunc(F-1)+1,
-    X = -trunc(-F),
-    X = -trunc(-F-1)-1,
-    X = -trunc(-F+1)+1,
+	       trunc_and_friends(F),
+	       trunc_and_friends(F),
+	       binary_to_list(term_to_binary(trunc_and_friends(F)))]),
+    X = trunc_and_friends(F),
+    X = trunc_and_friends(F+1)-1,
+    X = trunc_and_friends(F-1)+1,
+    X = -trunc_and_friends(-F),
+    X = -trunc_and_friends(-F-1)-1,
+    X = -trunc_and_friends(-F+1)+1,
 
     %% Bignums.
-    4294967305 = trunc(id(4294967305.7)),
-    -4294967305 = trunc(id(-4294967305.7)),
+    4294967305 = trunc_and_friends(4294967305.7),
+    -4294967305 = trunc_and_friends(-4294967305.7),
+    18446744073709551616 = trunc_and_friends(float(1 bsl 64)),
+    -18446744073709551616 = trunc_and_friends(-float(1 bsl 64)),
+
+    %% Random.
+    t_trunc_and_friends_rand(100),
     ok.
 
+t_trunc_and_friends_rand(0) ->
+    ok;
+t_trunc_and_friends_rand(N) ->
+    F0 = rand:uniform() * math:pow(10, 50*rand:normal()),
+    F = case rand:uniform() of
+	    U when U < 0.5 -> -F0;
+	    _ -> F0
+	end,
+    _ = trunc_and_friends(F),
+    t_trunc_and_friends_rand(N-1).
+
+trunc_and_friends(F) ->
+    Trunc = trunc(F),
+    Floor = floor(F),
+    Ceil = ceil(F),
+    Round = round(F),
+
+    Trunc = trunc(Trunc),
+    Floor = floor(Floor),
+    Ceil = ceil(Ceil),
+    Round = round(Round),
+
+    Trunc = trunc(float(Trunc)),
+    Floor = floor(float(Floor)),
+    Ceil = ceil(float(Ceil)),
+    Round = round(float(Round)),
+
+    true = Floor =< Trunc andalso Trunc =< Ceil,
+    true = Ceil - Floor =< 1,
+    true = Round =:= Floor orelse Round =:= Ceil,
+
+    if
+	F < 0 ->
+	    Trunc = Ceil;
+	true ->
+	    Trunc = Floor
+    end,
+    Trunc.
 
 %% Tests integer_to_binary/1.
 
diff --git a/erts/preloaded/ebin/erlang.beam b/erts/preloaded/ebin/erlang.beam
index c68debeabc..72c26a6b67 100644
--- a/erts/preloaded/ebin/erlang.beam
+++ b/erts/preloaded/ebin/erlang.beam
diff --git a/erts/preloaded/src/erlang.erl b/erts/preloaded/src/erlang.erl
index 652a954807..5bd73fe44d 100644
--- a/erts/preloaded/src/erlang.erl
+++ b/erts/preloaded/src/erlang.erl
@@ -100,7 +100,8 @@
 -export([binary_to_list/3, binary_to_term/1, binary_to_term/2]).
 -export([bit_size/1, bitsize/1, bitstring_to_list/1]).
 -export([bump_reductions/1, byte_size/1, call_on_load_function/1]).
--export([cancel_timer/1, cancel_timer/2, check_old_code/1, check_process_code/2,
+-export([cancel_timer/1, cancel_timer/2, ceil/1,
+	 check_old_code/1, check_process_code/2,
 	 check_process_code/3, crc32/1]).
 -export([crc32/2, crc32_combine/3, date/0, decode_packet/3]).
 -export([delete_element/2]).
@@ -109,7 +110,7 @@
 -export([error/1, error/2, exit/1, exit/2, external_size/1]).
 -export([external_size/2, finish_after_on_load/2, finish_loading/1, float/1]).
 -export([float_to_binary/1, float_to_binary/2,
-	 float_to_list/1, float_to_list/2]).
+	 float_to_list/1, float_to_list/2, floor/1]).
 -export([fun_info/2, fun_info_mfa/1, fun_to_list/1, function_exported/3]).
 -export([garbage_collect/0, garbage_collect/1, garbage_collect/2]).
 -export([garbage_collect_message_area/0, get/0, get/1, get_keys/0, get_keys/1]).
@@ -474,6 +475,13 @@ cancel_timer(_TimerRef) ->
 cancel_timer(_TimerRef, _Options) ->
     erlang:nif_error(undefined).
 
+%% ceil/1
+%% Shadowed by erl_bif_types: erlang:ceil/1
+-spec ceil(Number) -> integer() when
+      Number :: number().
+ceil(_) ->
+    erlang:nif_error(undef).
+
 %% check_old_code/1
 -spec check_old_code(Module) -> boolean() when
       Module :: module().
@@ -837,6 +845,13 @@ float_to_list(_Float) ->
 float_to_list(_Float, _Options) ->
     erlang:nif_error(undefined).
 
+%% floor/1
+%% Shadowed by erl_bif_types: erlang:floor/1
+-spec floor(Number) -> integer() when
+      Number :: number().
+floor(_) ->
+    erlang:nif_error(undef).
+
 %% fun_info/2
 -spec erlang:fun_info(Fun, Item) -> {Item, Info} when
       Fun :: function(),