What are the steps to convert the signed binary in two's (2's) complement representation to an integer in decimal system (in base ten)?
1. Is this a positive or a negative number?
1110 1110 0010 1011 0011 1101 1110 1011 1101 0100 0010 0001 1101 1110 0000 0101 is the binary representation of a negative integer, on 64 bits (8 Bytes).
- In a signed binary in two's complement representation, the first bit (the leftmost) indicates the sign, 1 = negative, 0 = positive.
2. Get the binary representation in one's complement.
* Run this step only if the number is negative
- Note on binary subtraction rules:
- 11 - 1 = 10; 10 - 1 = 01; 1 - 0 = 1; 1 - 1 = 0.
Subtract 1 from the initial binary number.
1110 1110 0010 1011 0011 1101 1110 1011 1101 0100 0010 0001 1101 1110 0000 0101 - 1 = 1110 1110 0010 1011 0011 1101 1110 1011 1101 0100 0010 0001 1101 1110 0000 0100
3. Get the binary representation of the positive (unsigned) number.
* Run this step only if the number is negative
Flip all the bits of the signed binary in one's complement representation (reverse the digits) - replace the bits set on 1 with 0s and the bits on 0 with 1s:
!(1110 1110 0010 1011 0011 1101 1110 1011 1101 0100 0010 0001 1101 1110 0000 0100) = 0001 0001 1101 0100 1100 0010 0001 0100 0010 1011 1101 1110 0010 0001 1111 1011
4. Map the unsigned binary number's digits versus the corresponding powers of 2 that their place value represent:
263
0 262
0 261
0 260
1 259
0 258
0 257
0 256
1 255
1 254
1 253
0 252
1 251
0 250
1 249
0 248
0 247
1 246
1 245
0 244
0 243
0 242
0 241
1 240
0 239
0 238
0 237
0 236
1 235
0 234
1 233
0 232
0 231
0 230
0 229
1 228
0 227
1 226
0 225
1 224
1 223
1 222
1 221
0 220
1 219
1 218
1 217
1 216
0 215
0 214
0 213
1 212
0 211
0 210
0 29
0 28
1 27
1 26
1 25
1 24
1 23
1 22
0 21
1 20
1
5. Multiply each bit by its corresponding power of 2 and add all the terms up.
0001 0001 1101 0100 1100 0010 0001 0100 0010 1011 1101 1110 0010 0001 1111 1011(2) =
(0 × 263 + 0 × 262 + 0 × 261 + 1 × 260 + 0 × 259 + 0 × 258 + 0 × 257 + 1 × 256 + 1 × 255 + 1 × 254 + 0 × 253 + 1 × 252 + 0 × 251 + 1 × 250 + 0 × 249 + 0 × 248 + 1 × 247 + 1 × 246 + 0 × 245 + 0 × 244 + 0 × 243 + 0 × 242 + 1 × 241 + 0 × 240 + 0 × 239 + 0 × 238 + 0 × 237 + 1 × 236 + 0 × 235 + 1 × 234 + 0 × 233 + 0 × 232 + 0 × 231 + 0 × 230 + 1 × 229 + 0 × 228 + 1 × 227 + 0 × 226 + 1 × 225 + 1 × 224 + 1 × 223 + 1 × 222 + 0 × 221 + 1 × 220 + 1 × 219 + 1 × 218 + 1 × 217 + 0 × 216 + 0 × 215 + 0 × 214 + 1 × 213 + 0 × 212 + 0 × 211 + 0 × 210 + 0 × 29 + 1 × 28 + 1 × 27 + 1 × 26 + 1 × 25 + 1 × 24 + 1 × 23 + 0 × 22 + 1 × 21 + 1 × 20)(10) =
(0 + 0 + 0 + 1 152 921 504 606 846 976 + 0 + 0 + 0 + 72 057 594 037 927 936 + 36 028 797 018 963 968 + 18 014 398 509 481 984 + 0 + 4 503 599 627 370 496 + 0 + 1 125 899 906 842 624 + 0 + 0 + 140 737 488 355 328 + 70 368 744 177 664 + 0 + 0 + 0 + 0 + 2 199 023 255 552 + 0 + 0 + 0 + 0 + 68 719 476 736 + 0 + 17 179 869 184 + 0 + 0 + 0 + 0 + 536 870 912 + 0 + 134 217 728 + 0 + 33 554 432 + 16 777 216 + 8 388 608 + 4 194 304 + 0 + 1 048 576 + 524 288 + 262 144 + 131 072 + 0 + 0 + 0 + 8 192 + 0 + 0 + 0 + 0 + 256 + 128 + 64 + 32 + 16 + 8 + 0 + 2 + 1)(10) =
(1 152 921 504 606 846 976 + 72 057 594 037 927 936 + 36 028 797 018 963 968 + 18 014 398 509 481 984 + 4 503 599 627 370 496 + 1 125 899 906 842 624 + 140 737 488 355 328 + 70 368 744 177 664 + 2 199 023 255 552 + 68 719 476 736 + 17 179 869 184 + 536 870 912 + 134 217 728 + 33 554 432 + 16 777 216 + 8 388 608 + 4 194 304 + 1 048 576 + 524 288 + 262 144 + 131 072 + 8 192 + 256 + 128 + 64 + 32 + 16 + 8 + 2 + 1)(10) =
1 284 865 185 598 546 427(10)
6. If needed, adjust the sign of the integer number by the first digit (leftmost) of the signed binary:
1110 1110 0010 1011 0011 1101 1110 1011 1101 0100 0010 0001 1101 1110 0000 0101(2) = -1 284 865 185 598 546 427(10)
The number 1110 1110 0010 1011 0011 1101 1110 1011 1101 0100 0010 0001 1101 1110 0000 0101(2), signed binary in two's (2's) complement representation, converted and written as an integer in decimal system (base ten):
1110 1110 0010 1011 0011 1101 1110 1011 1101 0100 0010 0001 1101 1110 0000 0101(2) = -1 284 865 185 598 546 427(10)
Spaces were used to group digits: for binary, by 4, for decimal, by 3.