1 files changed, 99 insertions, 0 deletions
diff --git a/lib/std/special/compiler_rt/comparetf2.zig b/lib/std/special/compiler_rt/comparetf2.zig
new file mode 100644
index 0000000000..05e5974558
--- /dev/null
+++ b/lib/std/special/compiler_rt/comparetf2.zig
@@ -0,0 +1,99 @@
+// TODO https://github.com/ziglang/zig/issues/641
+// and then make the return types of some of these functions the enum instead of c_int
+const LE_LESS = c_int(-1);
+const LE_EQUAL = c_int(0);
+const LE_GREATER = c_int(1);
+const LE_UNORDERED = c_int(1);
+
+const rep_t = u128;
+const srep_t = i128;
+
+const typeWidth = rep_t.bit_count;
+const significandBits = 112;
+const exponentBits = (typeWidth - significandBits - 1);
+const signBit = (rep_t(1) << (significandBits + exponentBits));
+const absMask = signBit - 1;
+const implicitBit = rep_t(1) << significandBits;
+const significandMask = implicitBit - 1;
+const exponentMask = absMask ^ significandMask;
+const infRep = exponentMask;
+
+const builtin = @import("builtin");
+const is_test = builtin.is_test;
+
+pub extern fn __letf2(a: f128, b: f128) c_int {
+    @setRuntimeSafety(is_test);
+
+    const aInt = @bitCast(rep_t, a);
+    const bInt = @bitCast(rep_t, b);
+
+    const aAbs: rep_t = aInt & absMask;
+    const bAbs: rep_t = bInt & absMask;
+
+    // If either a or b is NaN, they are unordered.
+    if (aAbs > infRep or bAbs > infRep) return LE_UNORDERED;
+
+    // If a and b are both zeros, they are equal.
+    if ((aAbs | bAbs) == 0) return LE_EQUAL;
+
+    // If at least one of a and b is positive, we get the same result comparing
+    // a and b as signed integers as we would with a floating-point compare.
+    return if ((aInt & bInt) >= 0)
+        if (aInt < bInt)
+            LE_LESS
+        else if (aInt == bInt)
+            LE_EQUAL
+        else
+            LE_GREATER
+    else
+    // Otherwise, both are negative, so we need to flip the sense of the
+    // comparison to get the correct result.  (This assumes a twos- or ones-
+    // complement integer representation; if integers are represented in a
+    // sign-magnitude representation, then this flip is incorrect).
+    if (aInt > bInt)
+        LE_LESS
+    else if (aInt == bInt)
+        LE_EQUAL
+    else
+        LE_GREATER;
+}
+
+// TODO https://github.com/ziglang/zig/issues/641
+// and then make the return types of some of these functions the enum instead of c_int
+const GE_LESS = c_int(-1);
+const GE_EQUAL = c_int(0);
+const GE_GREATER = c_int(1);
+const GE_UNORDERED = c_int(-1); // Note: different from LE_UNORDERED
+
+pub extern fn __getf2(a: f128, b: f128) c_int {
+    @setRuntimeSafety(is_test);
+
+    const aInt = @bitCast(srep_t, a);
+    const bInt = @bitCast(srep_t, b);
+    const aAbs = @bitCast(rep_t, aInt) & absMask;
+    const bAbs = @bitCast(rep_t, bInt) & absMask;
+
+    if (aAbs > infRep or bAbs > infRep) return GE_UNORDERED;
+    if ((aAbs | bAbs) == 0) return GE_EQUAL;
+    return if ((aInt & bInt) >= 0)
+        if (aInt < bInt)
+            GE_LESS
+        else if (aInt == bInt)
+            GE_EQUAL
+        else
+            GE_GREATER
+    else if (aInt > bInt)
+        GE_LESS
+    else if (aInt == bInt)
+        GE_EQUAL
+    else
+        GE_GREATER;
+}
+
+pub extern fn __unordtf2(a: f128, b: f128) c_int {
+    @setRuntimeSafety(is_test);
+
+    const aAbs = @bitCast(rep_t, a) & absMask;
+    const bAbs = @bitCast(rep_t, b) & absMask;
+    return @boolToInt(aAbs > infRep or bAbs > infRep);
+}