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| 1 | - | |
| 1 | + | void deinterleave_split(int *a, int len) |
| 2 | {
| |
| 3 | if (2 == len) | |
| 4 | {
| |
| 5 | // not needed | |
| 6 | } | |
| 7 | else if (4 == len) | |
| 8 | {
| |
| 9 | int t = a[1]; | |
| 10 | a[1] = a[2]; | |
| 11 | a[2] = t; | |
| 12 | } | |
| 13 | else if (0 == (len % 4)) | |
| 14 | {
| |
| 15 | deinterleave_split(&a[0], len/2); | |
| 16 | deinterleave_split(&a[len/2], len/2); | |
| 17 | for (int i = len/4; i < len/2; i++) | |
| 18 | {
| |
| 19 | int t = a[i]; | |
| 20 | a[i] = a[i+len/4]; | |
| 21 | a[i+len/4] = t; | |
| 22 | } | |
| 23 | } | |
| 24 | else | |
| 25 | {
| |
| 26 | int t; | |
| 27 | deinterleave_split(&a[0], len-2); | |
| 28 | t = a[len-2]; | |
| 29 | memmove(&a[len/2],&a[len/2-1],sizeof(int)*(len/2-1)); | |
| 30 | a[len/2-1] = t; | |
| 31 | } | |
| 32 | } | |
| 33 | ||
| 34 | void interleave_split(int *a, int len) | |
| 35 | {
| |
| 36 | if (2 == len) | |
| 37 | {
| |
| 38 | // no need | |
| 39 | } | |
| 40 | else if (4 == len) | |
| 41 | {
| |
| 42 | int t = a[1]; | |
| 43 | a[1] = a[2]; | |
| 44 | a[2] = t; | |
| 45 | } | |
| 46 | else if (0 == (len % 4)) | |
| 47 | {
| |
| 48 | for (int i = len/4; i < len/2; i++) | |
| 49 | {
| |
| 50 | int t = a[i]; | |
| 51 | a[i] = a[i+len/4]; | |
| 52 | a[i+len/4] = t; | |
| 53 | } | |
| 54 | interleave_split(&a[0], len/2); | |
| 55 | interleave_split(&a[len/2], len/2); | |
| 56 | } | |
| 57 | else | |
| 58 | {
| |
| 59 | int t; | |
| 60 | t = a[len/2-1]; | |
| 61 | memmove(&a[len/2-1],&a[len/2],sizeof(int)*(len/2-1)); | |
| 62 | a[len-2] = t; | |
| 63 | interleave_split(&a[0], len-2); | |
| 64 | } | |
| 65 | } |
