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?
0100 0000 0000 1001 0001 1110 1011 1000 0101 0001 1110 1011 1000 0100 1100 1000 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
1 261
0 260
0 259
0 258
0 257
0 256
0 255
0 254
0 253
0 252
0 251
1 250
0 249
0 248
1 247
0 246
0 245
0 244
1 243
1 242
1 241
1 240
0 239
1 238
0 237
1 236
1 235
1 234
0 233
0 232
0 231
0 230
1 229
0 228
1 227
0 226
0 225
0 224
1 223
1 222
1 221
1 220
0 219
1 218
0 217
1 216
1 215
1 214
0 213
0 212
0 211
0 210
1 29
0 28
0 27
1 26
1 25
0 24
0 23
1 22
0 21
0 20
0
5. Multiply each bit by its corresponding power of 2 and add all the terms up.
0100 0000 0000 1001 0001 1110 1011 1000 0101 0001 1110 1011 1000 0100 1100 1000(2) =
(0 × 263 + 1 × 262 + 0 × 261 + 0 × 260 + 0 × 259 + 0 × 258 + 0 × 257 + 0 × 256 + 0 × 255 + 0 × 254 + 0 × 253 + 0 × 252 + 1 × 251 + 0 × 250 + 0 × 249 + 1 × 248 + 0 × 247 + 0 × 246 + 0 × 245 + 1 × 244 + 1 × 243 + 1 × 242 + 1 × 241 + 0 × 240 + 1 × 239 + 0 × 238 + 1 × 237 + 1 × 236 + 1 × 235 + 0 × 234 + 0 × 233 + 0 × 232 + 0 × 231 + 1 × 230 + 0 × 229 + 1 × 228 + 0 × 227 + 0 × 226 + 0 × 225 + 1 × 224 + 1 × 223 + 1 × 222 + 1 × 221 + 0 × 220 + 1 × 219 + 0 × 218 + 1 × 217 + 1 × 216 + 1 × 215 + 0 × 214 + 0 × 213 + 0 × 212 + 0 × 211 + 1 × 210 + 0 × 29 + 0 × 28 + 1 × 27 + 1 × 26 + 0 × 25 + 0 × 24 + 1 × 23 + 0 × 22 + 0 × 21 + 0 × 20)(10) =
(0 + 4 611 686 018 427 387 904 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 2 251 799 813 685 248 + 0 + 0 + 281 474 976 710 656 + 0 + 0 + 0 + 17 592 186 044 416 + 8 796 093 022 208 + 4 398 046 511 104 + 2 199 023 255 552 + 0 + 549 755 813 888 + 0 + 137 438 953 472 + 68 719 476 736 + 34 359 738 368 + 0 + 0 + 0 + 0 + 1 073 741 824 + 0 + 268 435 456 + 0 + 0 + 0 + 16 777 216 + 8 388 608 + 4 194 304 + 2 097 152 + 0 + 524 288 + 0 + 131 072 + 65 536 + 32 768 + 0 + 0 + 0 + 0 + 1 024 + 0 + 0 + 128 + 64 + 0 + 0 + 8 + 0 + 0 + 0)(10) =
(4 611 686 018 427 387 904 + 2 251 799 813 685 248 + 281 474 976 710 656 + 17 592 186 044 416 + 8 796 093 022 208 + 4 398 046 511 104 + 2 199 023 255 552 + 549 755 813 888 + 137 438 953 472 + 68 719 476 736 + 34 359 738 368 + 1 073 741 824 + 268 435 456 + 16 777 216 + 8 388 608 + 4 194 304 + 2 097 152 + 524 288 + 131 072 + 65 536 + 32 768 + 1 024 + 128 + 64 + 8)(10) =
4 614 253 070 214 989 000(10)
6. If needed, adjust the sign of the integer number by the first digit (leftmost) of the signed binary:
0100 0000 0000 1001 0001 1110 1011 1000 0101 0001 1110 1011 1000 0100 1100 1000(2) = 4 614 253 070 214 989 000(10)
The number 0100 0000 0000 1001 0001 1110 1011 1000 0101 0001 1110 1011 1000 0100 1100 1000(2), signed binary in two's (2's) complement representation, converted and written as an integer in decimal system (base ten):
0100 0000 0000 1001 0001 1110 1011 1000 0101 0001 1110 1011 1000 0100 1100 1000(2) = 4 614 253 070 214 989 000(10)
Spaces were used to group digits: for binary, by 4, for decimal, by 3.