LXR coreboot/src/lib/nrv2b.c

   1// This GETBIT is supposed to work on little endian
   2// 32bit systems. The algorithm will definitely need
   3// some fixing on other systems, but it might not be
   4// a problem since the nrv2b binary behaves the same..
   5
   6#ifndef ENDIAN
   7#define ENDIAN   0
   8#endif
   9#ifndef BITSIZE
  10#define BITSIZE 32
  11#endif
  12
  13#define GETBIT_8(bb, src, ilen) \
  14    (((bb = bb & 0x7f ? bb*2 : ((unsigned)src[ilen++]*2+1)) >> 8) & 1)
  15
  16#define GETBIT_LE16(bb, src, ilen) \
  17    (bb*=2,bb&0xffff ? (bb>>16)&1 : (ilen+=2,((bb=(src[ilen-2]+src[ilen-1]*256u)*2+1)>>16)&1))
  18#define GETBIT_LE32(bb, src, ilen) \
  19    (bc > 0 ? ((bb>>--bc)&1) : (bc=31,\
  20    bb=*(const uint32_t *)((src)+ilen),ilen+=4,(bb>>31)&1))
  21
  22#if ENDIAN == 0 && BITSIZE == 8
  23#define GETBIT(bb, src, ilen) GETBIT_8(bb, src, ilen)
  24#endif
  25#if ENDIAN == 0 && BITSIZE == 16
  26#define GETBIT(bb, src, ilen) GETBIT_LE16(bb, src, ilen)
  27#endif
  28#if ENDIAN == 0 && BITSIZE == 32
  29#define GETBIT(bb, src, ilen) GETBIT_LE32(bb, src, ilen)
  30#endif
  31static unsigned long unrv2b(uint8_t * src, uint8_t * dst, unsigned long *ilen_p)
  32{
  33        unsigned long ilen = 0, olen = 0, last_m_off = 1;
  34        uint32_t bb = 0;
  35        unsigned bc = 0;
  36        const uint8_t *m_pos;
  37
  38        // skip length
  39        src += 4;
  40        /* FIXME: check olen with the length stored in first 4 bytes */
  41
  42        for (;;) {
  43                unsigned int m_off, m_len;
  44                while (GETBIT(bb, src, ilen)) {
  45                        dst[olen++] = src[ilen++];
  46                }
  47
  48                m_off = 1;
  49                do {
  50                        m_off = m_off * 2 + GETBIT(bb, src, ilen);
  51                } while (!GETBIT(bb, src, ilen));
  52                if (m_off == 2) {
  53                        m_off = last_m_off;
  54                } else {
  55                        m_off = (m_off - 3) * 256 + src[ilen++];
  56                        if (m_off == 0xffffffffU)
  57                                break;
  58                        last_m_off = ++m_off;
  59                }
  60
  61                m_len = GETBIT(bb, src, ilen);
  62                m_len = m_len * 2 + GETBIT(bb, src, ilen);
  63                if (m_len == 0) {
  64                        m_len++;
  65                        do {
  66                                m_len = m_len * 2 + GETBIT(bb, src, ilen);
  67                        } while (!GETBIT(bb, src, ilen));
  68                        m_len += 2;
  69                }
  70                m_len += (m_off > 0xd00);
  71
  72                m_pos = dst + olen - m_off;
  73                dst[olen++] = *m_pos++;
  74                do {
  75                        dst[olen++] = *m_pos++;
  76                } while (--m_len > 0);
  77        }
  78
  79        *ilen_p = ilen;
  80
  81        return olen;
  82
  83}
  84
  85