diff options
Diffstat (limited to 'src/libbio/bseek.c')
-rw-r--r-- | src/libbio/bseek.c | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/src/libbio/bseek.c b/src/libbio/bseek.c new file mode 100644 index 00000000..f4325fb8 --- /dev/null +++ b/src/libbio/bseek.c @@ -0,0 +1,56 @@ +#include "lib9.h" +#include <bio.h> + +off_t +Bseek(Biobuf *bp, off_t offset, int base) +{ + off_t n, d; + + switch(bp->state) { + default: + fprint(2, "Bseek: unknown state %d\n", bp->state); + return Beof; + + case Bracteof: + bp->state = Bractive; + bp->icount = 0; + bp->gbuf = bp->ebuf; + + case Bractive: + n = offset; + if(base == 1) { + n += Boffset(bp); + base = 0; + } + + /* + * try to seek within buffer + */ + if(base == 0) { + d = n - Boffset(bp); + bp->icount += d; + if(d >= 0) { + if(bp->icount <= 0) + return n; + } else { + if(bp->ebuf - bp->gbuf >= -bp->icount) + return n; + } + } + + /* + * reset the buffer + */ + n = lseek(bp->fid, n, base); + bp->icount = 0; + bp->gbuf = bp->ebuf; + break; + + case Bwactive: + Bflush(bp); + n = lseek(bp->fid, offset, base); + break; + } + bp->offset = n; + return n; +} |