From 8a6a14e1f5006543f63117fb1f0a81a0b1024ebd Mon Sep 17 00:00:00 2001
From: volth <volth@volth.com>
Date: Sat, 12 May 2018 16:50:39 +0000
Subject: [PATCH] add `mod' and bitwise builtins

---
 src/libexpr/parser.y   |  7 ++++++
 src/libexpr/primops.cc | 53 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 60 insertions(+)

diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index eee48887d..6beb28868 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -338,6 +338,13 @@ expr_op
   | expr_op '-' expr_op { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__sub")), $1), $3); }
   | expr_op '*' expr_op { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__mul")), $1), $3); }
   | expr_op '/' expr_op { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__div")), $1), $3); }
+  | expr_op '%' expr_op { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__mod")), $1), $3); }
+  | expr_op '&' expr_op { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__bin_and")), $1), $3); }
+  | expr_op '|' expr_op { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__bin_or")), $1), $3); }
+  | expr_op '^' expr_op { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__bin_xor")), $1), $3); }
+  | expr_op '<<' expr_op { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__bin_shl")), $1), $3); }
+  | expr_op '>>>' expr_op { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__bin_unsigned_shr")), $1), $3); }
+  | expr_op '>>' expr_op { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__bin_signed_shr")), $1), $3); }
   | expr_op CONCAT expr_op { $$ = new ExprOpConcatLists(CUR_POS, $1, $3); }
   | expr_app
   ;
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 57dc7bd12..fa17f06b4 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1676,6 +1676,52 @@ static void prim_div(EvalState & state, const Pos & pos, Value * * args, Value &
     }
 }
 
+static void prim_mod(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    NixFloat f2 = state.forceFloat(*args[1], pos);
+    if (f2 == 0) throw EvalError(format("division by zero, at %1%") % pos);
+
+    if (args[0]->type == tFloat || args[1]->type == tFloat) {
+        mkFloat(v, state.forceFloat(*args[0], pos) % state.forceFloat(*args[1], pos));
+    } else {
+        NixInt i1 = state.forceInt(*args[0], pos);
+        NixInt i2 = state.forceInt(*args[1], pos);
+        /* Avoid division overflow as it might raise SIGFPE. */
+        if (i1 == std::numeric_limits<NixInt>::min() && i2 == -1)
+            throw EvalError(format("overflow in integer division, at %1%") % pos);
+        mkInt(v, i1 % i2);
+    }
+}
+
+static void prim_bin_and(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    mkInt(v, state.forceInt(*args[0], pos) & state.forceInt(*args[1], pos));
+}
+
+static void prim_bin_or(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    mkInt(v, state.forceInt(*args[0], pos) | state.forceInt(*args[1], pos));
+}
+
+static void prim_bin_xor(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    mkInt(v, state.forceInt(*args[0], pos) ^ state.forceInt(*args[1], pos));
+}
+
+static void prim_bin_shl(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    mkInt(v, state.forceInt(*args[0], pos) << (state.forceInt(*args[1], pos) & 63));
+}
+
+static void prim_bin_unsigned_shr(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    mkInt(v, (unsigned long)state.forceInt(*args[0], pos) >> (state.forceInt(*args[1], pos) & 63));
+}
+
+static void prim_bin_signed_shr(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    mkInt(v, (signed long)state.forceInt(*args[0], pos) >> (state.forceInt(*args[1], pos) & 63));
+}
 
 static void prim_lessThan(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
@@ -2221,6 +2267,13 @@ void EvalState::createBaseEnv()
     addPrimOp("__sub", 2, prim_sub);
     addPrimOp("__mul", 2, prim_mul);
     addPrimOp("__div", 2, prim_div);
+    addPrimOp("__mod", 2, prim_mod);
+    addPrimOp("__bin_and", 2, prim_bin_and);
+    addPrimOp("__bin_or", 2, prim_bin_or);
+    addPrimOp("__bin_xor", 2, prim_bin_xor);
+    addPrimOp("__bin_shl", 2, prim_bin_shl);
+    addPrimOp("__bin_unsigned_shr", 2, prim_bin_unsigned_shr);
+    addPrimOp("__bin_signed_shr", 2, prim_bin_signed_shr);
     addPrimOp("__lessThan", 2, prim_lessThan);
 
     // String manipulation