diff options
Diffstat (limited to 'src/lib')
| -rw-r--r-- | src/lib/nrv2b.c | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/src/lib/nrv2b.c b/src/lib/nrv2b.c new file mode 100644 index 0000000000..f912347e3a --- /dev/null +++ b/src/lib/nrv2b.c @@ -0,0 +1,61 @@ +#include <stdlib.h> +#include <stddef.h> + +// This GETBIT is supposed to work on little endian +// 32bit systems. The algorithm will definitely need +// some fixing on other systems, but it might not be +// a problem since the nrv2b binary behaves the same.. + +#define GETBIT(bb, src, ilen) \ + (bc > 0 ? ((bb>>--bc)&1) : (bc=31,\ + bb=*(const uint32_t *)((src)+ilen),ilen+=4,(bb>>31)&1)) + +static void unrv2b(uint8_t * src, uint8_t * dst) +{ + unsigned long ilen = 0, olen = 0, last_m_off = 1; + uint32_t bb = 0; + unsigned bc = 0; + const uint8_t *m_pos; + + // skip length + src += 4; + + for (;;) { + unsigned int m_off, m_len; + while (GETBIT(bb, src, ilen)) { + dst[olen++] = src[ilen++]; + } + + m_off = 1; + do { + m_off = m_off * 2 + GETBIT(bb, src, ilen); + } while (!GETBIT(bb, src, ilen)); + if (m_off == 2) { + m_off = last_m_off; + } else { + m_off = (m_off - 3) * 256 + src[ilen++]; + if (m_off == 0xffffffffU) + break; + last_m_off = ++m_off; + } + + m_len = GETBIT(bb, src, ilen); + m_len = m_len * 2 + GETBIT(bb, src, ilen); + if (m_len == 0) { + m_len++; + do { + m_len = m_len * 2 + GETBIT(bb, src, ilen); + } while (!GETBIT(bb, src, ilen)); + m_len += 2; + } + m_len += (m_off > 0xd00); + + m_pos = dst + olen - m_off; + dst[olen++] = *m_pos++; + do { + dst[olen++] = *m_pos++; + } while (--m_len > 0); + } + +} + |