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?
0000 0000 0110 1000 0110 1000 0010 0010 1010 0110 0110 1000 0010 0110 1110 1101 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
0 261
0 260
0 259
0 258
0 257
0 256
0 255
0 254
1 253
1 252
0 251
1 250
0 249
0 248
0 247
0 246
1 245
1 244
0 243
1 242
0 241
0 240
0 239
0 238
0 237
1 236
0 235
0 234
0 233
1 232
0 231
1 230
0 229
1 228
0 227
0 226
1 225
1 224
0 223
0 222
1 221
1 220
0 219
1 218
0 217
0 216
0 215
0 214
0 213
1 212
0 211
0 210
1 29
1 28
0 27
1 26
1 25
1 24
0 23
1 22
1 21
0 20
1
5. Multiply each bit by its corresponding power of 2 and add all the terms up.
0000 0000 0110 1000 0110 1000 0010 0010 1010 0110 0110 1000 0010 0110 1110 1101(2) =
(0 × 263 + 0 × 262 + 0 × 261 + 0 × 260 + 0 × 259 + 0 × 258 + 0 × 257 + 0 × 256 + 0 × 255 + 1 × 254 + 1 × 253 + 0 × 252 + 1 × 251 + 0 × 250 + 0 × 249 + 0 × 248 + 0 × 247 + 1 × 246 + 1 × 245 + 0 × 244 + 1 × 243 + 0 × 242 + 0 × 241 + 0 × 240 + 0 × 239 + 0 × 238 + 1 × 237 + 0 × 236 + 0 × 235 + 0 × 234 + 1 × 233 + 0 × 232 + 1 × 231 + 0 × 230 + 1 × 229 + 0 × 228 + 0 × 227 + 1 × 226 + 1 × 225 + 0 × 224 + 0 × 223 + 1 × 222 + 1 × 221 + 0 × 220 + 1 × 219 + 0 × 218 + 0 × 217 + 0 × 216 + 0 × 215 + 0 × 214 + 1 × 213 + 0 × 212 + 0 × 211 + 1 × 210 + 1 × 29 + 0 × 28 + 1 × 27 + 1 × 26 + 1 × 25 + 0 × 24 + 1 × 23 + 1 × 22 + 0 × 21 + 1 × 20)(10) =
(0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 18 014 398 509 481 984 + 9 007 199 254 740 992 + 0 + 2 251 799 813 685 248 + 0 + 0 + 0 + 0 + 70 368 744 177 664 + 35 184 372 088 832 + 0 + 8 796 093 022 208 + 0 + 0 + 0 + 0 + 0 + 137 438 953 472 + 0 + 0 + 0 + 8 589 934 592 + 0 + 2 147 483 648 + 0 + 536 870 912 + 0 + 0 + 67 108 864 + 33 554 432 + 0 + 0 + 4 194 304 + 2 097 152 + 0 + 524 288 + 0 + 0 + 0 + 0 + 0 + 8 192 + 0 + 0 + 1 024 + 512 + 0 + 128 + 64 + 32 + 0 + 8 + 4 + 0 + 1)(10) =
(18 014 398 509 481 984 + 9 007 199 254 740 992 + 2 251 799 813 685 248 + 70 368 744 177 664 + 35 184 372 088 832 + 8 796 093 022 208 + 137 438 953 472 + 8 589 934 592 + 2 147 483 648 + 536 870 912 + 67 108 864 + 33 554 432 + 4 194 304 + 2 097 152 + 524 288 + 8 192 + 1 024 + 512 + 128 + 64 + 32 + 8 + 4 + 1)(10) =
29 387 895 607 928 557(10)
6. If needed, adjust the sign of the integer number by the first digit (leftmost) of the signed binary:
0000 0000 0110 1000 0110 1000 0010 0010 1010 0110 0110 1000 0010 0110 1110 1101(2) = 29 387 895 607 928 557(10)
The number 0000 0000 0110 1000 0110 1000 0010 0010 1010 0110 0110 1000 0010 0110 1110 1101(2), signed binary in two's (2's) complement representation, converted and written as an integer in decimal system (base ten):
0000 0000 0110 1000 0110 1000 0010 0010 1010 0110 0110 1000 0010 0110 1110 1101(2) = 29 387 895 607 928 557(10)
Spaces were used to group digits: for binary, by 4, for decimal, by 3.