Improve f128 standard library support

* Add functions: floor128, ceil128, trunc128 and round128
* Add corresponding tests

lib/std/math.zig

@@ -122,6 +122,11 @@ pub fn forceEval(value: var) void {
             const p = @ptrCast(*volatile f64, &x);
             p.* = x;
         },
+        f128 => {
+            var x: f128 = undefined;
+            const p = @ptrCast(*volatile f128, &x);
+            p.* = x;
+        },
         else => {
             @compileError("forceEval not implemented for " ++ @typeName(T));
         },

lib/std/math/ceil.zig

@@ -20,6 +20,7 @@ pub fn ceil(x: var) @TypeOf(x) {
     return switch (T) {
         f32 => ceil32(x),
         f64 => ceil64(x),
+        f128 => ceil128(x),
         else => @compileError("ceil not implemented for " ++ @typeName(T)),
     };
 }
@@ -86,9 +87,37 @@ fn ceil64(x: f64) f64 {
     }
 }
 
+fn ceil128(x: f128) f128 {
+    const u = @bitCast(u128, x);
+    const e = (u >> 112) & 0x7FFF;
+    var y: f128 = undefined;
+
+    if (e >= 0x3FFF + 112 or x == 0) return x;
+
+    if (u >> 127 != 0) {
+        y = x - math.f128_toint + math.f128_toint - x;
+    } else {
+        y = x + math.f128_toint - math.f128_toint - x;
+    }
+
+    if (e <= 0x3FFF - 1) {
+        math.forceEval(y);
+        if (u >> 127 != 0) {
+            return -0.0;
+        } else {
+            return 1.0;
+        }
+    } else if (y < 0) {
+        return x + y + 1;
+    } else {
+        return x + y;
+    }
+}
+
 test "math.ceil" {
     expect(ceil(@as(f32, 0.0)) == ceil32(0.0));
     expect(ceil(@as(f64, 0.0)) == ceil64(0.0));
+    expect(ceil(@as(f128, 0.0)) == ceil128(0.0));
 }
 
 test "math.ceil32" {
@@ -103,6 +132,12 @@ test "math.ceil64" {
     expect(ceil64(0.2) == 1.0);
 }
 
+test "math.ceil128" {
+    expect(ceil128(1.3) == 2.0);
+    expect(ceil128(-1.3) == -1.0);
+    expect(ceil128(0.2) == 1.0);
+}
+
 test "math.ceil32.special" {
     expect(ceil32(0.0) == 0.0);
     expect(ceil32(-0.0) == -0.0);
@@ -118,3 +153,11 @@ test "math.ceil64.special" {
     expect(math.isNegativeInf(ceil64(-math.inf(f64))));
     expect(math.isNan(ceil64(math.nan(f64))));
 }
+
+test "math.ceil128.special" {
+    expect(ceil128(0.0) == 0.0);
+    expect(ceil128(-0.0) == -0.0);
+    expect(math.isPositiveInf(ceil128(math.inf(f128))));
+    expect(math.isNegativeInf(ceil128(-math.inf(f128))));
+    expect(math.isNan(ceil128(math.nan(f128))));
+}

lib/std/math/floor.zig

@@ -21,6 +21,7 @@ pub fn floor(x: var) @TypeOf(x) {
         f16 => floor16(x),
         f32 => floor32(x),
         f64 => floor64(x),
+        f128 => floor128(x),
         else => @compileError("floor not implemented for " ++ @typeName(T)),
     };
 }
@@ -122,10 +123,38 @@ fn floor64(x: f64) f64 {
     }
 }
 
+fn floor128(x: f128) f128 {
+    const u = @bitCast(u128, x);
+    const e = (u >> 112) & 0x7FFF;
+    var y: f128 = undefined;
+
+    if (e >= 0x3FFF + 112 or x == 0) return x;
+
+    if (u >> 127 != 0) {
+        y = x - math.f128_toint + math.f128_toint - x;
+    } else {
+        y = x + math.f128_toint - math.f128_toint - x;
+    }
+
+    if (e <= 0x3FFF - 1) {
+        math.forceEval(y);
+        if (u >> 127 != 0) {
+            return -1.0;
+        } else {
+            return 0.0;
+        }
+    } else if (y > 0) {
+        return x + y - 1;
+    } else {
+        return x + y;
+    }
+}
+
 test "math.floor" {
     expect(floor(@as(f16, 1.3)) == floor16(1.3));
     expect(floor(@as(f32, 1.3)) == floor32(1.3));
     expect(floor(@as(f64, 1.3)) == floor64(1.3));
+    expect(floor(@as(f128, 1.3)) == floor128(1.3));
 }
 
 test "math.floor16" {
@@ -146,6 +175,12 @@ test "math.floor64" {
     expect(floor64(0.2) == 0.0);
 }
 
+test "math.floor128" {
+    expect(floor128(1.3) == 1.0);
+    expect(floor128(-1.3) == -2.0);
+    expect(floor128(0.2) == 0.0);
+}
+
 test "math.floor16.special" {
     expect(floor16(0.0) == 0.0);
     expect(floor16(-0.0) == -0.0);
@@ -169,3 +204,11 @@ test "math.floor64.special" {
     expect(math.isNegativeInf(floor64(-math.inf(f64))));
     expect(math.isNan(floor64(math.nan(f64))));
 }
+
+test "math.floor128.special" {
+    expect(floor128(0.0) == 0.0);
+    expect(floor128(-0.0) == -0.0);
+    expect(math.isPositiveInf(floor128(math.inf(f128))));
+    expect(math.isNegativeInf(floor128(-math.inf(f128))));
+    expect(math.isNan(floor128(math.nan(f128))));
+}

lib/std/math/round.zig

@@ -20,6 +20,7 @@ pub fn round(x: var) @TypeOf(x) {
     return switch (T) {
         f32 => round32(x),
         f64 => round64(x),
+        f128 => round128(x),
         else => @compileError("round not implemented for " ++ @typeName(T)),
     };
 }
@@ -90,9 +91,43 @@ fn round64(x_: f64) f64 {
     }
 }
 
+fn round128(x_: f128) f128 {
+    var x = x_;
+    const u = @bitCast(u128, x);
+    const e = (u >> 112) & 0x7FFF;
+    var y: f128 = undefined;
+
+    if (e >= 0x3FFF + 112) {
+        return x;
+    }
+    if (u >> 127 != 0) {
+        x = -x;
+    }
+    if (e < 0x3FFF - 1) {
+        math.forceEval(x + math.f64_toint);
+        return 0 * @bitCast(f128, u);
+    }
+
+    y = x + math.f128_toint - math.f128_toint - x;
+    if (y > 0.5) {
+        y = y + x - 1;
+    } else if (y <= -0.5) {
+        y = y + x + 1;
+    } else {
+        y = y + x;
+    }
+
+    if (u >> 127 != 0) {
+        return -y;
+    } else {
+        return y;
+    }
+}
+
 test "math.round" {
     expect(round(@as(f32, 1.3)) == round32(1.3));
     expect(round(@as(f64, 1.3)) == round64(1.3));
+    expect(round(@as(f128, 1.3)) == round128(1.3));
 }
 
 test "math.round32" {
@@ -109,6 +144,13 @@ test "math.round64" {
     expect(round64(1.8) == 2.0);
 }
 
+test "math.round128" {
+    expect(round128(1.3) == 1.0);
+    expect(round128(-1.3) == -1.0);
+    expect(round128(0.2) == 0.0);
+    expect(round128(1.8) == 2.0);
+}
+
 test "math.round32.special" {
     expect(round32(0.0) == 0.0);
     expect(round32(-0.0) == -0.0);
@@ -124,3 +166,11 @@ test "math.round64.special" {
     expect(math.isNegativeInf(round64(-math.inf(f64))));
     expect(math.isNan(round64(math.nan(f64))));
 }
+
+test "math.round128.special" {
+    expect(round128(0.0) == 0.0);
+    expect(round128(-0.0) == -0.0);
+    expect(math.isPositiveInf(round128(math.inf(f128))));
+    expect(math.isNegativeInf(round128(-math.inf(f128))));
+    expect(math.isNan(round128(math.nan(f128))));
+}

lib/std/math/trunc.zig

@@ -20,6 +20,7 @@ pub fn trunc(x: var) @TypeOf(x) {
     return switch (T) {
         f32 => trunc32(x),
         f64 => trunc64(x),
+        f128 => trunc128(x),
         else => @compileError("trunc not implemented for " ++ @typeName(T)),
     };
 }
@@ -66,9 +67,31 @@ fn trunc64(x: f64) f64 {
     }
 }
 
+fn trunc128(x: f128) f128 {
+    const u = @bitCast(u128, x);
+    var e = @intCast(i32, ((u >> 112) & 0x7FFF)) - 0x3FFF + 16;
+    var m: u128 = undefined;
+
+    if (e >= 112 + 16) {
+        return x;
+    }
+    if (e < 16) {
+        e = 1;
+    }
+
+    m = @as(u128, maxInt(u128)) >> @intCast(u7, e);
+    if (u & m == 0) {
+        return x;
+    } else {
+        math.forceEval(x + 0x1p120);
+        return @bitCast(f128, u & ~m);
+    }
+}
+
 test "math.trunc" {
     expect(trunc(@as(f32, 1.3)) == trunc32(1.3));
     expect(trunc(@as(f64, 1.3)) == trunc64(1.3));
+    expect(trunc(@as(f128, 1.3)) == trunc128(1.3));
 }
 
 test "math.trunc32" {
@@ -83,6 +106,12 @@ test "math.trunc64" {
     expect(trunc64(0.2) == 0.0);
 }
 
+test "math.trunc128" {
+    expect(trunc128(1.3) == 1.0);
+    expect(trunc128(-1.3) == -1.0);
+    expect(trunc128(0.2) == 0.0);
+}
+
 test "math.trunc32.special" {
     expect(trunc32(0.0) == 0.0); // 0x3F800000
     expect(trunc32(-0.0) == -0.0);
@@ -98,3 +127,11 @@ test "math.trunc64.special" {
     expect(math.isNegativeInf(trunc64(-math.inf(f64))));
     expect(math.isNan(trunc64(math.nan(f64))));
 }
+
+test "math.trunc128.special" {
+    expect(trunc128(0.0) == 0.0);
+    expect(trunc128(-0.0) == -0.0);
+    expect(math.isPositiveInf(trunc128(math.inf(f128))));
+    expect(math.isNegativeInf(trunc128(-math.inf(f128))));
+    expect(math.isNan(trunc128(math.nan(f128))));
+}