diff options
Diffstat (limited to 'src/libs/7zip/unix/C/Delta.c')
-rw-r--r-- | src/libs/7zip/unix/C/Delta.c | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/src/libs/7zip/unix/C/Delta.c b/src/libs/7zip/unix/C/Delta.c new file mode 100644 index 000000000..2b327f15f --- /dev/null +++ b/src/libs/7zip/unix/C/Delta.c @@ -0,0 +1,62 @@ +/* Delta.c -- Delta converter +2009-05-26 : Igor Pavlov : Public domain */ + +#include "Delta.h" + +void Delta_Init(Byte *state) +{ + unsigned i; + for (i = 0; i < DELTA_STATE_SIZE; i++) + state[i] = 0; +} + +static void MyMemCpy(Byte *dest, const Byte *src, unsigned size) +{ + unsigned i; + for (i = 0; i < size; i++) + dest[i] = src[i]; +} + +void Delta_Encode(Byte *state, unsigned delta, Byte *data, SizeT size) +{ + Byte buf[DELTA_STATE_SIZE]; + unsigned j = 0; + MyMemCpy(buf, state, delta); + { + SizeT i; + for (i = 0; i < size;) + { + for (j = 0; j < delta && i < size; i++, j++) + { + Byte b = data[i]; + data[i] = (Byte)(b - buf[j]); + buf[j] = b; + } + } + } + if (j == delta) + j = 0; + MyMemCpy(state, buf + j, delta - j); + MyMemCpy(state + delta - j, buf, j); +} + +void Delta_Decode(Byte *state, unsigned delta, Byte *data, SizeT size) +{ + Byte buf[DELTA_STATE_SIZE]; + unsigned j = 0; + MyMemCpy(buf, state, delta); + { + SizeT i; + for (i = 0; i < size;) + { + for (j = 0; j < delta && i < size; i++, j++) + { + buf[j] = data[i] = (Byte)(buf[j] + data[i]); + } + } + } + if (j == delta) + j = 0; + MyMemCpy(state, buf + j, delta - j); + MyMemCpy(state + delta - j, buf, j); +} |