diff options
Diffstat (limited to 'Source')
| -rw-r--r-- | Source/Basetypes/BigFloat.cs | 114 |
1 files changed, 69 insertions, 45 deletions
diff --git a/Source/Basetypes/BigFloat.cs b/Source/Basetypes/BigFloat.cs index d93f7d7b..0b35c237 100644 --- a/Source/Basetypes/BigFloat.cs +++ b/Source/Basetypes/BigFloat.cs @@ -25,23 +25,27 @@ namespace Microsoft.Basetypes // the internal representation [Rep] - internal readonly BIM mantissa; //TODO: restrict mantissa. Note that mantissa includes the sign + internal readonly Boolean[] mantissa; //Note that the first element of the mantissa array is the least significant bit for coding simplicity [Rep] - internal readonly int exponent; //TODO: restrict exponent to be 8-bits wide + internal readonly Boolean isNegative; //The left-most (sign) bit in the float representation [Rep] - internal readonly int mantissaSize; //Represents the maximum size of the mantissa + internal readonly int exponent; [Rep] - internal readonly int exponentSize; //Represents the maximum size of the exponent + internal readonly int exponentSize; //The maximum bit size of the exponent public BIM Mantissa { get { - return mantissa; + BIM toReturn = 0; + for (int i = 0; i < mantissa.Length; i++) + if (mantissa[i]) + toReturn += (int) Math.Pow(2, i); + return isNegative ? -toReturn : toReturn; } } public int Exponent { get { - return exponent; + return exponent - (int)Math.Pow(2, exponentSize - 1); //account for shift } } @@ -49,7 +53,7 @@ namespace Microsoft.Basetypes { get { - return mantissaSize; + return mantissa.Length; } } @@ -95,11 +99,11 @@ namespace Microsoft.Basetypes { switch (vals.Length) { case 1: - return Round(decimal.Parse(vals[0]), 23, 8); + return Round(vals[0], 23, 8); case 2: return new BigFloat(BIM.Parse(vals[0]), Int32.Parse(vals[1]), 23, 8); case 3: - return Round(decimal.Parse(vals[0]), Int32.Parse(vals[1]), Int32.Parse(vals[2])); + return Round(vals[0], Int32.Parse(vals[1]), Int32.Parse(vals[2])); case 4: return new BigFloat(BIM.Parse(vals[0]), Int32.Parse(vals[1]), Int32.Parse(vals[2]), Int32.Parse(vals[3])); default: @@ -112,14 +116,17 @@ namespace Microsoft.Basetypes } internal BigFloat(BIM mantissa, int exponent, int mantissaSize, int exponentSize) { - this.mantissaSize = mantissaSize; - this.exponentSize = mantissaSize; - this.mantissa = mantissa; + this.mantissa = new Boolean[mantissaSize]; + this.exponentSize = exponentSize; this.exponent = exponent; + //TODO: Add overflow check for exponent vs exponent size + this.isNegative = mantissa < 0; + if (this.isNegative) + mantissa = -mantissa; } - private int maxMantissa() { return (int)Math.Pow(2, mantissaSize); } - private int maxExponent() { return (int)Math.Pow(2, exponentSize); } + private int maxExponent() { return (int)Math.Pow(2, exponentSize - 1) - 1; } + private int minExponent() { return -(int)Math.Pow(2, exponentSize - 1); } @@ -139,21 +146,38 @@ namespace Microsoft.Basetypes [Pure] public override int GetHashCode() { - return this.mantissa.GetHashCode() * 13 + this.exponent.GetHashCode(); + return Mantissa.GetHashCode() * 13 + Exponent.GetHashCode(); } [Pure] public override string/*!*/ ToString() { //TODO: modify to reflect floating points Contract.Ensures(Contract.Result<string>() != null); - return String.Format("{0}e{1}", this.mantissa.ToString(), this.exponent.ToString()); + return String.Format("{0}e{1}", Mantissa.ToString(), Exponent.ToString()); } //////////////////////////////////////////////////////////////////////////// // Conversion operations - public static BigFloat Round(decimal d, int mantissaSize, int exponentSize) + public static BigFloat Round(String value, int mantissaSize, int exponentSize) + { + int i = value.IndexOf('.'); + if (i == -1) + return Round(BIM.Parse(value), 0, mantissaSize, exponentSize); + return Round(BIM.Parse(value.Substring(0, i - 1)), BIM.Parse(value.Substring(i + 1, value.Length - i - 1)), mantissaSize, exponentSize); + } + + /// <summary> + /// Converts value.dec_value to a float with mantissaSize, exponentSize + /// Returns the result of this calculation + /// </summary> + /// <param name="value"></param> + /// <param name="power"></param> + /// <param name="mantissaSize"></param> + /// <param name="exponentSize"></param> + /// <returns></returns> + public static BigFloat Round(BIM value, BIM dec_value, int mantissaSize, int exponentSize) { //TODO: round the given decimal to the nearest fp value return new BigFloat(0, 0, mantissaSize, exponentSize); } @@ -167,8 +191,8 @@ namespace Microsoft.Basetypes /// <param name="ceiling">Ceiling (rounded towards positive infinity)</param> public void FloorCeiling(out BIM floor, out BIM ceiling) { //TODO: fix for fp functionality - BIM n = this.mantissa; - int e = this.exponent; + BIM n = Mantissa; + int e = Exponent; if (n.IsZero) { floor = ceiling = n; } else if (0 <= e) { @@ -183,7 +207,7 @@ namespace Microsoft.Basetypes n = n / two; // Division rounds towards negative infinity } - if (this.mantissa >= 0) { + if (!isNegative) { floor = n; ceiling = n + 1; } else { @@ -197,26 +221,26 @@ namespace Microsoft.Basetypes [Pure] public String ToDecimalString(int maxDigits) { //TODO: fix for fp functionality - string s = this.mantissa.ToString(); - int digits = (this.mantissa >= 0) ? s.Length : s.Length - 1; + string s = Mantissa.ToString(); + int digits = (isNegative) ? s.Length - 1 : s.Length; BIM max = BIM.Pow(10, maxDigits); BIM min = -max; - if (this.exponent >= 0) { - if (maxDigits < digits || maxDigits - digits < this.exponent) { - return String.Format("{0}.0", (this.mantissa >= 0) ? max.ToString() : min.ToString()); + if (Exponent >= 0) { + if (maxDigits < digits || maxDigits - digits < Exponent) { + return String.Format("{0}.0", (!isNegative) ? max.ToString() : min.ToString()); } else { - return String.Format("{0}{1}.0", s, new string('0', this.exponent)); + return String.Format("{0}{1}.0", s, new string('0', Exponent)); } } else { - int exp = -this.exponent; + int exp = -Exponent; if (exp < digits) { int intDigits = digits - exp; if (maxDigits < intDigits) { - return String.Format("{0}.0", (this.mantissa >= 0) ? max.ToString() : min.ToString()); + return String.Format("{0}.0", (!isNegative) ? max.ToString() : min.ToString()); } else { int fracDigits = Math.Min(maxDigits, digits - intDigits); @@ -233,9 +257,9 @@ namespace Microsoft.Basetypes [Pure] public string ToDecimalString() { //TODO: fix for fp functionality - string m = this.mantissa.ToString(); - var e = this.exponent; - if (0 <= this.exponent) { + string m = Mantissa.ToString(); + var e = Exponent; + if (0 <= Exponent) { return m + Zeros(e) + ".0"; } else { e = -e; @@ -288,7 +312,7 @@ namespace Microsoft.Basetypes public BigFloat Abs { //TODO: fix for fp functionality get { - return new BigFloat(BIM.Abs(this.mantissa), this.exponent, this.mantissaSize, this.exponentSize); + return new BigFloat(BIM.Abs(Mantissa), Exponent, MantissaSize, ExponentSize); } } @@ -296,7 +320,7 @@ namespace Microsoft.Basetypes public BigFloat Negate { //TODO: Modify for correct fp functionality get { - return new BigFloat(BIM.Negate(this.mantissa), this.exponent, this.mantissaSize, this.exponentSize); + return new BigFloat(BIM.Negate(Mantissa), Exponent, MantissaSize, ExponentSize); } } @@ -308,15 +332,15 @@ namespace Microsoft.Basetypes [Pure] public static BigFloat operator +(BigFloat x, BigFloat y) { //TODO: Modify for correct fp functionality - BIM m1 = x.mantissa; - int e1 = x.exponent; - BIM m2 = y.mantissa; - int e2 = y.exponent; + BIM m1 = x.Mantissa; + int e1 = x.Exponent; + BIM m2 = y.Mantissa; + int e2 = y.Exponent; if (e2 < e1) { - m1 = y.mantissa; - e1 = y.exponent; - m2 = x.mantissa; - e2 = x.exponent; + m1 = y.Mantissa; + e1 = y.Exponent; + m2 = x.Mantissa; + e2 = x.Exponent; } while (e2 > e1) { @@ -335,7 +359,7 @@ namespace Microsoft.Basetypes [Pure] public static BigFloat operator *(BigFloat x, BigFloat y) { //TODO: modify for correct fp functionality - return new BigFloat(x.mantissa * y.mantissa, x.exponent + y.exponent, Math.Max(x.MantissaSize, y.MantissaSize), Math.Max(x.ExponentSize, y.ExponentSize)); + return new BigFloat(x.Mantissa * y.Mantissa, x.Exponent + y.Exponent, Math.Max(x.MantissaSize, y.MantissaSize), Math.Max(x.ExponentSize, y.ExponentSize)); } @@ -344,19 +368,19 @@ namespace Microsoft.Basetypes public bool IsPositive { get { - return (this.mantissa > BIM.Zero); + return (Mantissa > BIM.Zero); } } public bool IsNegative { get { - return (this.mantissa < BIM.Zero); + return (Mantissa < BIM.Zero); } } public bool IsZero { get { - return this.mantissa.IsZero && this.exponent == 0; + return Mantissa.IsZero && Exponent == 0; } } |