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 0100 0100 0111 1100 0000 0000 0000 0001 0000 0001 1111 0010 0001 1100 1010 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
1 257
0 256
0 255
0 254
1 253
0 252
0 251
0 250
1 249
1 248
1 247
1 246
1 245
0 244
0 243
0 242
0 241
0 240
0 239
0 238
0 237
0 236
0 235
0 234
0 233
0 232
0 231
0 230
0 229
0 228
1 227
0 226
0 225
0 224
0 223
0 222
0 221
0 220
1 219
1 218
1 217
1 216
1 215
0 214
0 213
1 212
0 211
0 210
0 29
0 28
1 27
1 26
1 25
0 24
0 23
1 22
0 21
1 20
0
5. Multiply each bit by its corresponding power of 2 and add all the terms up.
0000 0100 0100 0111 1100 0000 0000 0000 0001 0000 0001 1111 0010 0001 1100 1010(2) =
(0 × 263 + 0 × 262 + 0 × 261 + 0 × 260 + 0 × 259 + 1 × 258 + 0 × 257 + 0 × 256 + 0 × 255 + 1 × 254 + 0 × 253 + 0 × 252 + 0 × 251 + 1 × 250 + 1 × 249 + 1 × 248 + 1 × 247 + 1 × 246 + 0 × 245 + 0 × 244 + 0 × 243 + 0 × 242 + 0 × 241 + 0 × 240 + 0 × 239 + 0 × 238 + 0 × 237 + 0 × 236 + 0 × 235 + 0 × 234 + 0 × 233 + 0 × 232 + 0 × 231 + 0 × 230 + 0 × 229 + 1 × 228 + 0 × 227 + 0 × 226 + 0 × 225 + 0 × 224 + 0 × 223 + 0 × 222 + 0 × 221 + 1 × 220 + 1 × 219 + 1 × 218 + 1 × 217 + 1 × 216 + 0 × 215 + 0 × 214 + 1 × 213 + 0 × 212 + 0 × 211 + 0 × 210 + 0 × 29 + 1 × 28 + 1 × 27 + 1 × 26 + 0 × 25 + 0 × 24 + 1 × 23 + 0 × 22 + 1 × 21 + 0 × 20)(10) =
(0 + 0 + 0 + 0 + 0 + 288 230 376 151 711 744 + 0 + 0 + 0 + 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 + 70 368 744 177 664 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 268 435 456 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 1 048 576 + 524 288 + 262 144 + 131 072 + 65 536 + 0 + 0 + 8 192 + 0 + 0 + 0 + 0 + 256 + 128 + 64 + 0 + 0 + 8 + 0 + 2 + 0)(10) =
(288 230 376 151 711 744 + 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 + 70 368 744 177 664 + 268 435 456 + 1 048 576 + 524 288 + 262 144 + 131 072 + 65 536 + 8 192 + 256 + 128 + 64 + 8 + 2)(10) =
308 426 206 001 177 034(10)
6. If needed, adjust the sign of the integer number by the first digit (leftmost) of the signed binary:
0000 0100 0100 0111 1100 0000 0000 0000 0001 0000 0001 1111 0010 0001 1100 1010(2) = 308 426 206 001 177 034(10)
The number 0000 0100 0100 0111 1100 0000 0000 0000 0001 0000 0001 1111 0010 0001 1100 1010(2), signed binary in two's (2's) complement representation, converted and written as an integer in decimal system (base ten):
0000 0100 0100 0111 1100 0000 0000 0000 0001 0000 0001 1111 0010 0001 1100 1010(2) = 308 426 206 001 177 034(10)
Spaces were used to group digits: for binary, by 4, for decimal, by 3.