github.com/jeffallen/go-ethereum@v1.1.4-0.20150910155051-571d3236c49c/accounts/abi/numbers.go (about)

     1  // Copyright 2015 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package abi
    18  
    19  import (
    20  	"math/big"
    21  	"reflect"
    22  
    23  	"github.com/ethereum/go-ethereum/common"
    24  )
    25  
    26  var big_t = reflect.TypeOf(&big.Int{})
    27  var ubig_t = reflect.TypeOf(&big.Int{})
    28  var byte_t = reflect.TypeOf(byte(0))
    29  var byte_ts = reflect.TypeOf([]byte(nil))
    30  var uint_t = reflect.TypeOf(uint(0))
    31  var uint8_t = reflect.TypeOf(uint8(0))
    32  var uint16_t = reflect.TypeOf(uint16(0))
    33  var uint32_t = reflect.TypeOf(uint32(0))
    34  var uint64_t = reflect.TypeOf(uint64(0))
    35  var int_t = reflect.TypeOf(int(0))
    36  var int8_t = reflect.TypeOf(int8(0))
    37  var int16_t = reflect.TypeOf(int16(0))
    38  var int32_t = reflect.TypeOf(int32(0))
    39  var int64_t = reflect.TypeOf(int64(0))
    40  
    41  var uint_ts = reflect.TypeOf([]uint(nil))
    42  var uint8_ts = reflect.TypeOf([]uint8(nil))
    43  var uint16_ts = reflect.TypeOf([]uint16(nil))
    44  var uint32_ts = reflect.TypeOf([]uint32(nil))
    45  var uint64_ts = reflect.TypeOf([]uint64(nil))
    46  var ubig_ts = reflect.TypeOf([]*big.Int(nil))
    47  
    48  var int_ts = reflect.TypeOf([]int(nil))
    49  var int8_ts = reflect.TypeOf([]int8(nil))
    50  var int16_ts = reflect.TypeOf([]int16(nil))
    51  var int32_ts = reflect.TypeOf([]int32(nil))
    52  var int64_ts = reflect.TypeOf([]int64(nil))
    53  var big_ts = reflect.TypeOf([]*big.Int(nil))
    54  
    55  // U256 will ensure unsigned 256bit on big nums
    56  func U256(n *big.Int) []byte {
    57  	return common.LeftPadBytes(common.U256(n).Bytes(), 32)
    58  }
    59  
    60  func S256(n *big.Int) []byte {
    61  	sint := common.S256(n)
    62  	ret := common.LeftPadBytes(sint.Bytes(), 32)
    63  	if sint.Cmp(common.Big0) < 0 {
    64  		for i, b := range ret {
    65  			if b == 0 {
    66  				ret[i] = 1
    67  				continue
    68  			}
    69  			break
    70  		}
    71  	}
    72  
    73  	return ret
    74  }
    75  
    76  // S256 will ensure signed 256bit on big nums
    77  func U2U256(n uint64) []byte {
    78  	return U256(big.NewInt(int64(n)))
    79  }
    80  
    81  func S2S256(n int64) []byte {
    82  	return S256(big.NewInt(n))
    83  }
    84  
    85  // packNum packs the given number (using the reflect value) and will cast it to appropriate number representation
    86  func packNum(value reflect.Value, to byte) []byte {
    87  	switch kind := value.Kind(); kind {
    88  	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
    89  		if to == UintTy {
    90  			return U2U256(value.Uint())
    91  		} else {
    92  			return S2S256(int64(value.Uint()))
    93  		}
    94  	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
    95  		if to == UintTy {
    96  			return U2U256(uint64(value.Int()))
    97  		} else {
    98  			return S2S256(value.Int())
    99  		}
   100  	case reflect.Ptr:
   101  		// This only takes care of packing and casting. No type checking is done here. It should be done prior to using this function.
   102  		if to == UintTy {
   103  			return U256(value.Interface().(*big.Int))
   104  		} else {
   105  			return S256(value.Interface().(*big.Int))
   106  		}
   107  
   108  	}
   109  
   110  	return nil
   111  }
   112  
   113  // checks whether the given reflect value is signed. This also works for slices with a number type
   114  func isSigned(v reflect.Value) bool {
   115  	switch v.Type() {
   116  	case ubig_ts, big_ts, big_t, ubig_t:
   117  		return true
   118  	case int_ts, int8_ts, int16_ts, int32_ts, int64_ts, int_t, int8_t, int16_t, int32_t, int64_t:
   119  		return true
   120  	}
   121  	return false
   122  }