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 0001 1100 1011 1001 0111 0001 0111 1110 1111 1010 1011 1110 0011 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
0 253
0 252
1 251
1 250
1 249
0 248
0 247
1 246
0 245
1 244
1 243
1 242
0 241
0 240
1 239
0 238
1 237
1 236
1 235
0 234
0 233
0 232
1 231
0 230
1 229
1 228
1 227
1 226
1 225
1 224
0 223
1 222
1 221
1 220
1 219
1 218
0 217
1 216
0 215
1 214
0 213
1 212
1 211
1 210
1 29
1 28
0 27
0 26
0 25
1 24
1 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 0001 1100 1011 1001 0111 0001 0111 1110 1111 1010 1011 1110 0011 1101(2) =
(0 × 263 + 0 × 262 + 0 × 261 + 0 × 260 + 0 × 259 + 0 × 258 + 0 × 257 + 0 × 256 + 0 × 255 + 0 × 254 + 0 × 253 + 1 × 252 + 1 × 251 + 1 × 250 + 0 × 249 + 0 × 248 + 1 × 247 + 0 × 246 + 1 × 245 + 1 × 244 + 1 × 243 + 0 × 242 + 0 × 241 + 1 × 240 + 0 × 239 + 1 × 238 + 1 × 237 + 1 × 236 + 0 × 235 + 0 × 234 + 0 × 233 + 1 × 232 + 0 × 231 + 1 × 230 + 1 × 229 + 1 × 228 + 1 × 227 + 1 × 226 + 1 × 225 + 0 × 224 + 1 × 223 + 1 × 222 + 1 × 221 + 1 × 220 + 1 × 219 + 0 × 218 + 1 × 217 + 0 × 216 + 1 × 215 + 0 × 214 + 1 × 213 + 1 × 212 + 1 × 211 + 1 × 210 + 1 × 29 + 0 × 28 + 0 × 27 + 0 × 26 + 1 × 25 + 1 × 24 + 1 × 23 + 1 × 22 + 0 × 21 + 1 × 20)(10) =
(0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 4 503 599 627 370 496 + 2 251 799 813 685 248 + 1 125 899 906 842 624 + 0 + 0 + 140 737 488 355 328 + 0 + 35 184 372 088 832 + 17 592 186 044 416 + 8 796 093 022 208 + 0 + 0 + 1 099 511 627 776 + 0 + 274 877 906 944 + 137 438 953 472 + 68 719 476 736 + 0 + 0 + 0 + 4 294 967 296 + 0 + 1 073 741 824 + 536 870 912 + 268 435 456 + 134 217 728 + 67 108 864 + 33 554 432 + 0 + 8 388 608 + 4 194 304 + 2 097 152 + 1 048 576 + 524 288 + 0 + 131 072 + 0 + 32 768 + 0 + 8 192 + 4 096 + 2 048 + 1 024 + 512 + 0 + 0 + 0 + 32 + 16 + 8 + 4 + 0 + 1)(10) =
(4 503 599 627 370 496 + 2 251 799 813 685 248 + 1 125 899 906 842 624 + 140 737 488 355 328 + 35 184 372 088 832 + 17 592 186 044 416 + 8 796 093 022 208 + 1 099 511 627 776 + 274 877 906 944 + 137 438 953 472 + 68 719 476 736 + 4 294 967 296 + 1 073 741 824 + 536 870 912 + 268 435 456 + 134 217 728 + 67 108 864 + 33 554 432 + 8 388 608 + 4 194 304 + 2 097 152 + 1 048 576 + 524 288 + 131 072 + 32 768 + 8 192 + 4 096 + 2 048 + 1 024 + 512 + 32 + 16 + 8 + 4 + 1)(10) =
8 085 196 460 703 293(10)
6. If needed, adjust the sign of the integer number by the first digit (leftmost) of the signed binary:
0000 0000 0001 1100 1011 1001 0111 0001 0111 1110 1111 1010 1011 1110 0011 1101(2) = 8 085 196 460 703 293(10)
The number 0000 0000 0001 1100 1011 1001 0111 0001 0111 1110 1111 1010 1011 1110 0011 1101(2), signed binary in two's (2's) complement representation, converted and written as an integer in decimal system (base ten):
0000 0000 0001 1100 1011 1001 0111 0001 0111 1110 1111 1010 1011 1110 0011 1101(2) = 8 085 196 460 703 293(10)
Spaces were used to group digits: for binary, by 4, for decimal, by 3.