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?
1100 0010 1101 0001 1011 1101 1100 0011 0100 0010 0010 0010 0010 0101 0010 1110 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.
1100 0010 1101 0001 1011 1101 1100 0011 0100 0010 0010 0010 0010 0101 0010 1110 - 1 = 1100 0010 1101 0001 1011 1101 1100 0011 0100 0010 0010 0010 0010 0101 0010 1101
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:
!(1100 0010 1101 0001 1011 1101 1100 0011 0100 0010 0010 0010 0010 0101 0010 1101) = 0011 1101 0010 1110 0100 0010 0011 1100 1011 1101 1101 1101 1101 1010 1101 0010
4. Map the unsigned binary number's digits versus the corresponding powers of 2 that their place value represent:
263
0 262
0 261
1 260
1 259
1 258
1 257
0 256
1 255
0 254
0 253
1 252
0 251
1 250
1 249
1 248
0 247
0 246
1 245
0 244
0 243
0 242
0 241
1 240
0 239
0 238
0 237
1 236
1 235
1 234
1 233
0 232
0 231
1 230
0 229
1 228
1 227
1 226
1 225
0 224
1 223
1 222
1 221
0 220
1 219
1 218
1 217
0 216
1 215
1 214
1 213
0 212
1 211
1 210
0 29
1 28
0 27
1 26
1 25
0 24
1 23
0 22
0 21
1 20
0
5. Multiply each bit by its corresponding power of 2 and add all the terms up.
0011 1101 0010 1110 0100 0010 0011 1100 1011 1101 1101 1101 1101 1010 1101 0010(2) =
(0 × 263 + 0 × 262 + 1 × 261 + 1 × 260 + 1 × 259 + 1 × 258 + 0 × 257 + 1 × 256 + 0 × 255 + 0 × 254 + 1 × 253 + 0 × 252 + 1 × 251 + 1 × 250 + 1 × 249 + 0 × 248 + 0 × 247 + 1 × 246 + 0 × 245 + 0 × 244 + 0 × 243 + 0 × 242 + 1 × 241 + 0 × 240 + 0 × 239 + 0 × 238 + 1 × 237 + 1 × 236 + 1 × 235 + 1 × 234 + 0 × 233 + 0 × 232 + 1 × 231 + 0 × 230 + 1 × 229 + 1 × 228 + 1 × 227 + 1 × 226 + 0 × 225 + 1 × 224 + 1 × 223 + 1 × 222 + 0 × 221 + 1 × 220 + 1 × 219 + 1 × 218 + 0 × 217 + 1 × 216 + 1 × 215 + 1 × 214 + 0 × 213 + 1 × 212 + 1 × 211 + 0 × 210 + 1 × 29 + 0 × 28 + 1 × 27 + 1 × 26 + 0 × 25 + 1 × 24 + 0 × 23 + 0 × 22 + 1 × 21 + 0 × 20)(10) =
(0 + 0 + 2 305 843 009 213 693 952 + 1 152 921 504 606 846 976 + 576 460 752 303 423 488 + 288 230 376 151 711 744 + 0 + 72 057 594 037 927 936 + 0 + 0 + 9 007 199 254 740 992 + 0 + 2 251 799 813 685 248 + 1 125 899 906 842 624 + 562 949 953 421 312 + 0 + 0 + 70 368 744 177 664 + 0 + 0 + 0 + 0 + 2 199 023 255 552 + 0 + 0 + 0 + 137 438 953 472 + 68 719 476 736 + 34 359 738 368 + 17 179 869 184 + 0 + 0 + 2 147 483 648 + 0 + 536 870 912 + 268 435 456 + 134 217 728 + 67 108 864 + 0 + 16 777 216 + 8 388 608 + 4 194 304 + 0 + 1 048 576 + 524 288 + 262 144 + 0 + 65 536 + 32 768 + 16 384 + 0 + 4 096 + 2 048 + 0 + 512 + 0 + 128 + 64 + 0 + 16 + 0 + 0 + 2 + 0)(10) =
(2 305 843 009 213 693 952 + 1 152 921 504 606 846 976 + 576 460 752 303 423 488 + 288 230 376 151 711 744 + 72 057 594 037 927 936 + 9 007 199 254 740 992 + 2 251 799 813 685 248 + 1 125 899 906 842 624 + 562 949 953 421 312 + 70 368 744 177 664 + 2 199 023 255 552 + 137 438 953 472 + 68 719 476 736 + 34 359 738 368 + 17 179 869 184 + 2 147 483 648 + 536 870 912 + 268 435 456 + 134 217 728 + 67 108 864 + 16 777 216 + 8 388 608 + 4 194 304 + 1 048 576 + 524 288 + 262 144 + 65 536 + 32 768 + 16 384 + 4 096 + 2 048 + 512 + 128 + 64 + 16 + 2)(10) =
4 408 533 913 893 198 546(10)
6. If needed, adjust the sign of the integer number by the first digit (leftmost) of the signed binary:
1100 0010 1101 0001 1011 1101 1100 0011 0100 0010 0010 0010 0010 0101 0010 1110(2) = -4 408 533 913 893 198 546(10)
The number 1100 0010 1101 0001 1011 1101 1100 0011 0100 0010 0010 0010 0010 0101 0010 1110(2), signed binary in two's (2's) complement representation, converted and written as an integer in decimal system (base ten):
1100 0010 1101 0001 1011 1101 1100 0011 0100 0010 0010 0010 0010 0101 0010 1110(2) = -4 408 533 913 893 198 546(10)
Spaces were used to group digits: for binary, by 4, for decimal, by 3.