update libchdr

[pcsx_rearmed.git] / deps / libchdr / deps / lzma-22.01 / src / Delta.c

/* Delta.c -- Delta converter\r
2021-02-09 : Igor Pavlov : Public domain */\r
\r
#include "Precomp.h"\r
\r
#include "Delta.h"\r
\r
void Delta_Init(Byte *state)\r
{\r
  unsigned i;\r
  for (i = 0; i < DELTA_STATE_SIZE; i++)\r
    state[i] = 0;\r
}\r
\r
\r
void Delta_Encode(Byte *state, unsigned delta, Byte *data, SizeT size)\r
{\r
  Byte temp[DELTA_STATE_SIZE];\r
\r
  if (size == 0)\r
    return;\r
\r
  {\r
    unsigned i = 0;\r
    do\r
      temp[i] = state[i];\r
    while (++i != delta);\r
  }\r
\r
  if (size <= delta)\r
  {\r
    unsigned i = 0, k;\r
    do\r
    {\r
      Byte b = *data;\r
      *data++ = (Byte)(b - temp[i]);\r
      temp[i] = b;\r
    }\r
    while (++i != size);\r
    \r
    k = 0;\r
    \r
    do\r
    {\r
      if (i == delta)\r
        i = 0;\r
      state[k] = temp[i++];\r
    }\r
    while (++k != delta);\r
    \r
    return;\r
  }\r
    \r
  {\r
    Byte *p = data + size - delta;\r
    {\r
      unsigned i = 0;\r
      do\r
        state[i] = *p++;\r
      while (++i != delta);\r
    }\r
    {\r
      const Byte *lim = data + delta;\r
      ptrdiff_t dif = -(ptrdiff_t)delta;\r
      \r
      if (((ptrdiff_t)size + dif) & 1)\r
      {\r
        --p;  *p = (Byte)(*p - p[dif]);\r
      }\r
\r
      while (p != lim)\r
      {\r
        --p;  *p = (Byte)(*p - p[dif]);\r
        --p;  *p = (Byte)(*p - p[dif]);\r
      }\r
      \r
      dif = -dif;\r
      \r
      do\r
      {\r
        --p;  *p = (Byte)(*p - temp[--dif]);\r
      }\r
      while (dif != 0);\r
    }\r
  }\r
}\r
\r
\r
void Delta_Decode(Byte *state, unsigned delta, Byte *data, SizeT size)\r
{\r
  unsigned i;\r
  const Byte *lim;\r
\r
  if (size == 0)\r
    return;\r
  \r
  i = 0;\r
  lim = data + size;\r
  \r
  if (size <= delta)\r
  {\r
    do\r
      *data = (Byte)(*data + state[i++]);\r
    while (++data != lim);\r
\r
    for (; delta != i; state++, delta--)\r
      *state = state[i];\r
    data -= i;\r
  }\r
  else\r
  {\r
    /*\r
    #define B(n) b ## n\r
    #define I(n) Byte B(n) = state[n];\r
    #define U(n) { B(n) = (Byte)((B(n)) + *data++); data[-1] = (B(n)); }\r
    #define F(n) if (data != lim) { U(n) }\r
\r
    if (delta == 1)\r
    {\r
      I(0)\r
      if ((lim - data) & 1) { U(0) }\r
      while (data != lim) { U(0) U(0) }\r
      data -= 1;\r
    }\r
    else if (delta == 2)\r
    {\r
      I(0) I(1)\r
      lim -= 1; while (data < lim) { U(0) U(1) }\r
      lim += 1; F(0)\r
      data -= 2;\r
    }\r
    else if (delta == 3)\r
    {\r
      I(0) I(1) I(2)\r
      lim -= 2; while (data < lim) { U(0) U(1) U(2) }\r
      lim += 2; F(0) F(1)\r
      data -= 3;\r
    }\r
    else if (delta == 4)\r
    {\r
      I(0) I(1) I(2) I(3)\r
      lim -= 3; while (data < lim) { U(0) U(1) U(2) U(3) }\r
      lim += 3; F(0) F(1) F(2)\r
      data -= 4;\r
    }\r
    else\r
    */\r
    {\r
      do\r
      {\r
        *data = (Byte)(*data + state[i++]);\r
        data++;\r
      }\r
      while (i != delta);\r
  \r
      {\r
        ptrdiff_t dif = -(ptrdiff_t)delta;\r
        do\r
          *data = (Byte)(*data + data[dif]);\r
        while (++data != lim);\r
        data += dif;\r
      }\r
    }\r
  }\r
\r
  do\r
    *state++ = *data;\r
  while (++data != lim);\r
}\r