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 1100 1100 0111 1011 0011 0011 1001 1011 1111 1110 0011 1100 0001 1001 1111 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
1 258
1 257
0 256
0 255
1 254
1 253
0 252
0 251
0 250
1 249
1 248
1 247
1 246
0 245
1 244
1 243
0 242
0 241
1 240
1 239
0 238
0 237
1 236
1 235
1 234
0 233
0 232
1 231
1 230
0 229
1 228
1 227
1 226
1 225
1 224
1 223
1 222
1 221
1 220
0 219
0 218
0 217
1 216
1 215
1 214
1 213
0 212
0 211
0 210
0 29
0 28
1 27
1 26
0 25
0 24
1 23
1 22
1 21
1 20
1
5. Multiply each bit by its corresponding power of 2 and add all the terms up.
0000 1100 1100 0111 1011 0011 0011 1001 1011 1111 1110 0011 1100 0001 1001 1111(2) =
(0 × 263 + 0 × 262 + 0 × 261 + 0 × 260 + 1 × 259 + 1 × 258 + 0 × 257 + 0 × 256 + 1 × 255 + 1 × 254 + 0 × 253 + 0 × 252 + 0 × 251 + 1 × 250 + 1 × 249 + 1 × 248 + 1 × 247 + 0 × 246 + 1 × 245 + 1 × 244 + 0 × 243 + 0 × 242 + 1 × 241 + 1 × 240 + 0 × 239 + 0 × 238 + 1 × 237 + 1 × 236 + 1 × 235 + 0 × 234 + 0 × 233 + 1 × 232 + 1 × 231 + 0 × 230 + 1 × 229 + 1 × 228 + 1 × 227 + 1 × 226 + 1 × 225 + 1 × 224 + 1 × 223 + 1 × 222 + 1 × 221 + 0 × 220 + 0 × 219 + 0 × 218 + 1 × 217 + 1 × 216 + 1 × 215 + 1 × 214 + 0 × 213 + 0 × 212 + 0 × 211 + 0 × 210 + 0 × 29 + 1 × 28 + 1 × 27 + 0 × 26 + 0 × 25 + 1 × 24 + 1 × 23 + 1 × 22 + 1 × 21 + 1 × 20)(10) =
(0 + 0 + 0 + 0 + 576 460 752 303 423 488 + 288 230 376 151 711 744 + 0 + 0 + 36 028 797 018 963 968 + 18 014 398 509 481 984 + 0 + 0 + 0 + 1 125 899 906 842 624 + 562 949 953 421 312 + 281 474 976 710 656 + 140 737 488 355 328 + 0 + 35 184 372 088 832 + 17 592 186 044 416 + 0 + 0 + 2 199 023 255 552 + 1 099 511 627 776 + 0 + 0 + 137 438 953 472 + 68 719 476 736 + 34 359 738 368 + 0 + 0 + 4 294 967 296 + 2 147 483 648 + 0 + 536 870 912 + 268 435 456 + 134 217 728 + 67 108 864 + 33 554 432 + 16 777 216 + 8 388 608 + 4 194 304 + 2 097 152 + 0 + 0 + 0 + 131 072 + 65 536 + 32 768 + 16 384 + 0 + 0 + 0 + 0 + 0 + 256 + 128 + 0 + 0 + 16 + 8 + 4 + 2 + 1)(10) =
(576 460 752 303 423 488 + 288 230 376 151 711 744 + 36 028 797 018 963 968 + 18 014 398 509 481 984 + 1 125 899 906 842 624 + 562 949 953 421 312 + 281 474 976 710 656 + 140 737 488 355 328 + 35 184 372 088 832 + 17 592 186 044 416 + 2 199 023 255 552 + 1 099 511 627 776 + 137 438 953 472 + 68 719 476 736 + 34 359 738 368 + 4 294 967 296 + 2 147 483 648 + 536 870 912 + 268 435 456 + 134 217 728 + 67 108 864 + 33 554 432 + 16 777 216 + 8 388 608 + 4 194 304 + 2 097 152 + 131 072 + 65 536 + 32 768 + 16 384 + 256 + 128 + 16 + 8 + 4 + 2 + 1)(10) =
920 901 709 434 438 047(10)
6. If needed, adjust the sign of the integer number by the first digit (leftmost) of the signed binary:
0000 1100 1100 0111 1011 0011 0011 1001 1011 1111 1110 0011 1100 0001 1001 1111(2) = 920 901 709 434 438 047(10)
The number 0000 1100 1100 0111 1011 0011 0011 1001 1011 1111 1110 0011 1100 0001 1001 1111(2), signed binary in two's (2's) complement representation, converted and written as an integer in decimal system (base ten):
0000 1100 1100 0111 1011 0011 0011 1001 1011 1111 1110 0011 1100 0001 1001 1111(2) = 920 901 709 434 438 047(10)
Spaces were used to group digits: for binary, by 4, for decimal, by 3.