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Move common floor() code into floorImpl()
This commit is contained in:
Iain Buclaw
parent
9ba75a9b11
commit
d68bc3da52
1 changed files with 103 additions and 196 deletions
299
std/math.d
299
std/math.d
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@ -186,8 +186,8 @@ template floatTraits(T)
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// SIGNPOS_BYTE is the index of the sign when represented as a ubyte array.
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// RECIP_EPSILON is the value such that (smallest_subnormal) * RECIP_EPSILON == T.min_normal
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enum T RECIP_EPSILON = (1/T.epsilon);
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static if (T.mant_dig == 24)
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{ // float
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static if (T.mant_dig == 24) // float
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{
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enum ushort EXPMASK = 0x7F80;
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enum ushort EXPBIAS = 0x3F00;
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enum uint EXPMASK_INT = 0x7F80_0000;
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@ -276,6 +276,101 @@ else
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enum MANTISSA_MSB = 0;
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}
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// Common code for math implementations.
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// Helper for floor/ceil
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T floorImpl(T)(T x) @trusted pure nothrow @nogc
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{
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// Bit clearing masks.
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static immutable ushort[17] BMASK = [
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0xffff, 0xfffe, 0xfffc, 0xfff8,
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0xfff0, 0xffe0, 0xffc0, 0xff80,
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0xff00, 0xfe00, 0xfc00, 0xf800,
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0xf000, 0xe000, 0xc000, 0x8000,
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0x0000,
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];
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alias F = floatTraits!(T);
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// Take care not to trigger library calls from the compiler,
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// while ensuring that we don't get defeated by some optimizers.
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union floatBits
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{
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T rv;
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ushort[T.sizeof/2] vu;
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}
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floatBits y = void;
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y.rv = x;
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// Find the exponent (power of 2)
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static if (T.mant_dig == 24) // float
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{
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int exp = ((y.vu[F.EXPPOS_SHORT] >> 7) & 0xff) - 0x7f;
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version (LittleEndian)
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int pos = 0;
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else
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int pos = 3;
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}
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else static if (T.mant_dig == 53) // double
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{
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int exp = ((y.vu[F.EXPPOS_SHORT] >> 4) & 0x7ff) - 0x3ff;
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version (LittleEndian)
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int pos = 0;
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else
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int pos = 3;
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}
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else static if (T.mant_dig == 64) // real80
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{
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int exp = (y.vu[F.EXPPOS_SHORT] & 0x7fff) - 0x3fff;
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version (LittleEndian)
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int pos = 0;
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else
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int pos = 4;
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}
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else if (T.mant_dig == 113) // quadruple
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{
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int exp = (y.vu[F.EXPPOS_SHORT] & 0x7fff) - 0x3fff;
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version (LittleEndian)
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int pos = 0;
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else
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int pos = 7;
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}
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else
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static assert(false, "Not implemented for this architecture");
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if (exp < 0)
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{
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if (x < 0.0)
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return -1.0;
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else
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return 0.0;
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}
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exp = (T.mant_dig - 1) - exp;
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// Zero 16 bits at a time.
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while (exp >= 16)
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{
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version (LittleEndian)
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y.vu[pos++] = 0;
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else
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y.vu[pos--] = 0;
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exp -= 16;
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}
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// Clear the remaining bits.
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if (exp > 0)
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y.vu[pos] &= BMASK[exp];
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if ((x < 0.0) && (x != y.rv))
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y.rv -= 1.0;
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return y.rv;
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}
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public:
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// Values obtained from Wolfram Alpha. 116 bits ought to be enough for anybody.
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@ -3016,7 +3111,7 @@ real ceil(real x) @trusted pure nothrow @nogc
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if (isNaN(x) || isInfinity(x))
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return x;
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real y = floor(x);
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real y = floorImpl(x);
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if (y < x)
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y += 1.0;
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@ -3045,7 +3140,7 @@ double ceil(double x) @trusted pure nothrow @nogc
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if (isNaN(x) || isInfinity(x))
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return x;
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double y = floor(x);
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double y = floorImpl(x);
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if (y < x)
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y += 1.0;
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@ -3073,7 +3168,7 @@ float ceil(float x) @trusted pure nothrow @nogc
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if (isNaN(x) || isInfinity(x))
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return x;
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float y = floor(x);
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float y = floorImpl(x);
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if (y < x)
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y += 1.0;
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@ -3121,89 +3216,11 @@ real floor(real x) @trusted pure nothrow @nogc
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}
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else
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{
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// Bit clearing masks.
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static immutable ushort[17] BMASK = [
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0xffff, 0xfffe, 0xfffc, 0xfff8,
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0xfff0, 0xffe0, 0xffc0, 0xff80,
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0xff00, 0xfe00, 0xfc00, 0xf800,
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0xf000, 0xe000, 0xc000, 0x8000,
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0x0000,
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];
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// Special cases.
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if (isNaN(x) || isInfinity(x) || x == 0.0)
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return x;
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alias F = floatTraits!(real);
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// Take care not to trigger library calls from the compiler,
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// while ensuring that we don't get defeated by some optimizers.
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union realBits
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{
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real rv;
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ushort[real.sizeof/2] vu;
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}
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realBits y = void;
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y.rv = x;
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// Find the exponent (power of 2)
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static if (real.mant_dig == 53)
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{
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int exp = ((y.vu[F.EXPPOS_SHORT] >> 4) & 0x7ff) - 0x3ff;
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version (LittleEndian)
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int pos = 0;
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else
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int pos = 3;
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}
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else static if (real.mant_dig == 64)
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{
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int exp = (y.vu[F.EXPPOS_SHORT] & 0x7fff) - 0x3fff;
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version (LittleEndian)
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int pos = 0;
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else
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int pos = 4;
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}
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else if (real.mant_dig == 113)
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{
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int exp = (y.vu[F.EXPPOS_SHORT] & 0x7fff) - 0x3fff;
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version (LittleEndian)
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int pos = 0;
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else
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int pos = 7;
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}
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else
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static assert(false, "Only 64-bit, 80-bit, and 128-bit reals are supported by floor()");
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if (exp < 0)
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{
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if (x < 0.0)
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return -1.0;
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else
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return 0.0;
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}
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exp = (real.mant_dig - 1) - exp;
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// Zero 16 bits at a time.
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while (exp >= 16)
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{
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version (LittleEndian)
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y.vu[pos++] = 0;
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else
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y.vu[pos--] = 0;
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exp -= 16;
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}
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// Clear the remaining bits.
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if (exp > 0)
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y.vu[pos] &= BMASK[exp];
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if ((x < 0.0) && (x != y.rv))
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y.rv -= 1.0;
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return y.rv;
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return floorImpl(x);
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}
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}
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@ -3224,66 +3241,11 @@ unittest
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// ditto
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double floor(double x) @trusted pure nothrow @nogc
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{
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// Bit clearing masks.
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static immutable ushort[17] BMASK = [
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0xffff, 0xfffe, 0xfffc, 0xfff8,
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0xfff0, 0xffe0, 0xffc0, 0xff80,
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0xff00, 0xfe00, 0xfc00, 0xf800,
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0xf000, 0xe000, 0xc000, 0x8000,
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0x0000,
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];
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// Special cases.
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if (isNaN(x) || isInfinity(x) || x == 0.0)
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return x;
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alias floatTraits!(double) F;
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// Take care not to trigger library calls from the compiler,
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// while ensuring that we don't get defeated by some optimizers.
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union doubleBits
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{
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double rv;
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ushort[4] vu;
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}
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doubleBits y = void;
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y.rv = x;
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// Find the exponent (power of 2)
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int exp = ((y.vu[F.EXPPOS_SHORT] >> 4) & 0x7ff) - 0x3ff;
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if (exp < 0)
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{
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if (x < 0.0)
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return -1.0;
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else
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return 0.0;
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}
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exp = (double.mant_dig - 1) - exp;
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version (LittleEndian)
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int pos = 0;
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else
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int pos = 3;
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// Zero 16 bits at a time.
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while (exp >= 16)
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{
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version (LittleEndian)
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y.vu[pos++] = 0;
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else
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y.vu[pos--] = 0;
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exp -= 16;
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}
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// Clear the remaining bits.
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if (exp > 0)
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y.vu[pos] &= BMASK[exp];
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if ((x < 0.0) && (x != y.rv))
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y.rv -= 1.0;
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return y.rv;
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return floorImpl(x);
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}
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unittest
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@ -3303,66 +3265,11 @@ unittest
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// ditto
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float floor(float x) @trusted pure nothrow @nogc
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{
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// Bit clearing masks.
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static immutable ushort[17] BMASK = [
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0xffff, 0xfffe, 0xfffc, 0xfff8,
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0xfff0, 0xffe0, 0xffc0, 0xff80,
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0xff00, 0xfe00, 0xfc00, 0xf800,
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0xf000, 0xe000, 0xc000, 0x8000,
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0x0000,
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];
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// Special cases.
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if (isNaN(x) || isInfinity(x) || x == 0.0)
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return x;
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alias floatTraits!(float) F;
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// Take care not to trigger library calls from the compiler,
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// while ensuring that we don't get defeated by some optimizers.
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union floatBits
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{
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float rv;
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ushort[2] vu;
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}
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floatBits y = void;
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y.rv = x;
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// Find the exponent (power of 2)
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int exp = ((y.vu[F.EXPPOS_SHORT] >> 7) & 0xff) - 0x7f;
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if (exp < 0)
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{
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if (x < 0.0)
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return -1.0;
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else
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return 0.0;
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}
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exp = (float.mant_dig - 1) - exp;
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version (LittleEndian)
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int pos = 0;
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else
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int pos = 3;
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// Zero 16 bits at a time.
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while (exp >= 16)
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{
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version (LittleEndian)
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y.vu[pos++] = 0;
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else
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y.vu[pos--] = 0;
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exp -= 16;
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}
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// Clear the remaining bits.
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if (exp > 0)
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y.vu[pos] &= BMASK[exp];
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if ((x < 0.0) && (x != y.rv))
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y.rv -= 1.0;
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return y.rv;
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return floorImpl(x);
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}
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unittest
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