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?
0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0101 0001 is the binary representation of a positive 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.
* Not the case - the number is positive
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:
* Not the case - the number is positive
4. Map the unsigned binary number's digits versus the corresponding powers of 2 that their place value represent:
263
0 262
1 261
1 260
0 259
0 258
1 257
1 256
0 255
0 254
1 253
1 252
0 251
0 250
1 249
1 248
0 247
0 246
1 245
1 244
0 243
0 242
1 241
1 240
0 239
0 238
1 237
1 236
0 235
0 234
1 233
1 232
0 231
0 230
1 229
1 228
0 227
0 226
1 225
1 224
0 223
0 222
1 221
1 220
0 219
0 218
1 217
1 216
0 215
0 214
1 213
1 212
0 211
0 210
1 29
1 28
0 27
0 26
1 25
0 24
1 23
0 22
0 21
0 20
1
5. Multiply each bit by its corresponding power of 2 and add all the terms up.
0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0101 0001(2) =
(0 × 263 + 1 × 262 + 1 × 261 + 0 × 260 + 0 × 259 + 1 × 258 + 1 × 257 + 0 × 256 + 0 × 255 + 1 × 254 + 1 × 253 + 0 × 252 + 0 × 251 + 1 × 250 + 1 × 249 + 0 × 248 + 0 × 247 + 1 × 246 + 1 × 245 + 0 × 244 + 0 × 243 + 1 × 242 + 1 × 241 + 0 × 240 + 0 × 239 + 1 × 238 + 1 × 237 + 0 × 236 + 0 × 235 + 1 × 234 + 1 × 233 + 0 × 232 + 0 × 231 + 1 × 230 + 1 × 229 + 0 × 228 + 0 × 227 + 1 × 226 + 1 × 225 + 0 × 224 + 0 × 223 + 1 × 222 + 1 × 221 + 0 × 220 + 0 × 219 + 1 × 218 + 1 × 217 + 0 × 216 + 0 × 215 + 1 × 214 + 1 × 213 + 0 × 212 + 0 × 211 + 1 × 210 + 1 × 29 + 0 × 28 + 0 × 27 + 1 × 26 + 0 × 25 + 1 × 24 + 0 × 23 + 0 × 22 + 0 × 21 + 1 × 20)(10) =
(0 + 4 611 686 018 427 387 904 + 2 305 843 009 213 693 952 + 0 + 0 + 288 230 376 151 711 744 + 144 115 188 075 855 872 + 0 + 0 + 18 014 398 509 481 984 + 9 007 199 254 740 992 + 0 + 0 + 1 125 899 906 842 624 + 562 949 953 421 312 + 0 + 0 + 70 368 744 177 664 + 35 184 372 088 832 + 0 + 0 + 4 398 046 511 104 + 2 199 023 255 552 + 0 + 0 + 274 877 906 944 + 137 438 953 472 + 0 + 0 + 17 179 869 184 + 8 589 934 592 + 0 + 0 + 1 073 741 824 + 536 870 912 + 0 + 0 + 67 108 864 + 33 554 432 + 0 + 0 + 4 194 304 + 2 097 152 + 0 + 0 + 262 144 + 131 072 + 0 + 0 + 16 384 + 8 192 + 0 + 0 + 1 024 + 512 + 0 + 0 + 64 + 0 + 16 + 0 + 0 + 0 + 1)(10) =
(4 611 686 018 427 387 904 + 2 305 843 009 213 693 952 + 288 230 376 151 711 744 + 144 115 188 075 855 872 + 18 014 398 509 481 984 + 9 007 199 254 740 992 + 1 125 899 906 842 624 + 562 949 953 421 312 + 70 368 744 177 664 + 35 184 372 088 832 + 4 398 046 511 104 + 2 199 023 255 552 + 274 877 906 944 + 137 438 953 472 + 17 179 869 184 + 8 589 934 592 + 1 073 741 824 + 536 870 912 + 67 108 864 + 33 554 432 + 4 194 304 + 2 097 152 + 262 144 + 131 072 + 16 384 + 8 192 + 1 024 + 512 + 64 + 16 + 1)(10) =
7 378 697 629 483 820 625(10)
6. If needed, adjust the sign of the integer number by the first digit (leftmost) of the signed binary:
0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0101 0001(2) = 7 378 697 629 483 820 625(10)
The number 0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0101 0001(2), signed binary in two's (2's) complement representation, converted and written as an integer in decimal system (base ten):
0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0110 0101 0001(2) = 7 378 697 629 483 820 625(10)
Spaces were used to group digits: for binary, by 4, for decimal, by 3.