1 /* Delta.c -- Delta converter
2 2009-05-26 : Igor Pavlov : Public domain */
8 void Delta_Init(Byte *state)
11 for (i = 0; i < DELTA_STATE_SIZE; i++)
15 static void MyMemCpy(Byte *dest, const Byte *src, unsigned size)
18 for (i = 0; i < size; i++)
22 void Delta_Encode(Byte *state, unsigned delta, Byte *data, SizeT size)
24 Byte buf[DELTA_STATE_SIZE];
26 MyMemCpy(buf, state, delta);
29 for (i = 0; i < size;)
31 for (j = 0; j < delta && i < size; i++, j++)
34 data[i] = (Byte)(b - buf[j]);
41 MyMemCpy(state, buf + j, delta - j);
42 MyMemCpy(state + delta - j, buf, j);
45 void Delta_Decode(Byte *state, unsigned delta, Byte *data, SizeT size)
47 Byte buf[DELTA_STATE_SIZE];
49 MyMemCpy(buf, state, delta);
52 for (i = 0; i < size;)
54 for (j = 0; j < delta && i < size; i++, j++)
56 buf[j] = data[i] = (Byte)(buf[j] + data[i]);
62 MyMemCpy(state, buf + j, delta - j);
63 MyMemCpy(state + delta - j, buf, j);