1 /* 2 * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org> 3 * 4 * Permission is hereby granted, free of charge, to any person obtaining 5 * a copy of this software and associated documentation files (the 6 * "Software"), to deal in the Software without restriction, including 7 * without limitation the rights to use, copy, modify, merge, publish, 8 * distribute, sublicense, and/or sell copies of the Software, and to 9 * permit persons to whom the Software is furnished to do so, subject to 10 * the following conditions: 11 * 12 * The above copyright notice and this permission notice shall be 13 * included in all copies or substantial portions of the Software. 14 * 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 18 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS 19 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN 20 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 22 * SOFTWARE. 23 */ 24 25 using System; 26 27 class TPointerExpr : TPointerBase { 28 29 string expr; 30 int min, max; 31 32 internal TPointerExpr(string expr, int min, int max) 33 { 34 this.expr = expr; 35 this.min = min; 36 this.max = max; 37 } 38 39 internal override bool ToBool(TValue vp) 40 { 41 throw new Exception("Cannot evaluate C-expr at compile time"); 42 } 43 44 internal override string ToString(TValue vp) 45 { 46 return ToCExpr(vp.x); 47 } 48 49 internal string ToCExpr(int off) 50 { 51 if (off == 0) { 52 return expr; 53 } else if (off > 0) { 54 return String.Format( 55 "(uint32_t)({0}) + {1}", expr, off); 56 } else { 57 return String.Format( 58 "(uint32_t)({0}) - {1}", expr, -(long)off); 59 } 60 } 61 62 internal int GetMaxBitLength(int off) 63 { 64 long rmin = (long)min + off; 65 long rmax = (long)max + off; 66 int numBits = 1; 67 if (rmin < 0) { 68 numBits = Math.Max(numBits, BitLength(rmin)); 69 } 70 if (rmax > 0) { 71 numBits = Math.Max(numBits, BitLength(rmax)); 72 } 73 return Math.Min(numBits, 32); 74 } 75 76 /* 77 * Get the minimal bit length of a value. This is for a signed 78 * representation: the length includes a sign bit. Thus, the 79 * returned value will be at least 1. 80 */ 81 static int BitLength(long v) 82 { 83 int num = 1; 84 if (v < 0) { 85 while (v != -1) { 86 num ++; 87 v >>= 1; 88 } 89 } else { 90 while (v != 0) { 91 num ++; 92 v >>= 1; 93 } 94 } 95 return num; 96 } 97 } 98