On Thu, Dec 13, 2007 at 02:31:49PM -0800, Junio C Hamano wrote:
> This implements earlier Linus's optimization to trim common lines at the
> end before passing them down to low level xdiff interface for all of our
> xdiff users.
>
> We could later enhance this to also trim common leading lines, but that
> would need tweaking of the output function to add the number of lines
> trimmed at the beginning to line numbers that appear in the hunk
> headers.
>
> Signed-off-by: Junio C Hamano <gitster@xxxxxxxxx>
> ---
> xdiff-interface.c | 34 +++++++++++++++++++++++++++++++++-
> 1 files changed, 33 insertions(+), 1 deletions(-)
>
> diff --git a/xdiff-interface.c b/xdiff-interface.c
> index 69a022c..f2cd488 100644
> --- a/xdiff-interface.c
> +++ b/xdiff-interface.c
> @@ -103,9 +103,41 @@ int xdiff_outf(void *priv_, mmbuffer_t *mb, int nbuf)
> return 0;
> }
>
> +/*
> + * Trim down common substring at the end of the buffers,
> + * but leave at least ctx lines at the end.
> + */
> +static void trim_common_tail(mmfile_t *a, mmfile_t *b, int ctx)
Should ctx be a long? (see comment below)
> +{
> + const int blk = 1024;
> + long trimmed = 0, recovered = 0;
> + int i;
> + char *ap = a->ptr + a->size;
> + char *bp = b->ptr + b->size;
> + long smaller = (a->size < b->size) ? a->size : b->size;
> +
> + while (blk + trimmed <= smaller && !memcmp(ap - blk, bp - blk, blk)) {
> + trimmed += blk;
> + ap -= blk;
> + bp -= blk;
> + }
> +
> + for (i = 0, recovered = 0; recovered < trimmed && i <= ctx; i++) {
> + while (recovered < trimmed && ap[recovered] != '\n')
> + recovered++;
> + }
> + a->size -= (trimmed - recovered);
> + b->size -= (trimmed - recovered);
> +}
> +
> int xdi_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp, xdemitconf_t const *xecfg, xdemitcb_t *xecb)
> {
> - return xdl_diff(mf1, mf2, xpp, xecfg, xecb);
> + mmfile_t a = *mf1;
> + mmfile_t b = *mf2;
> +
> + trim_common_tail(&a, &b, xecfg->ctxlen);
xdemitconf_t has the following definition
typedef struct s_xdemitconf {
long ctxlen;
unsigned long flags;
find_func_t find_func;
void *find_func_priv;
} xdemitconf_t;
So you are loosing some values in your trim_common_tail function by making ctx
only an int. (Not sure that it matters, but I noticed it while glancing over
your code).
> +
> + return xdl_diff(&a, &b, xpp, xecfg, xecb);
> }
>
> int read_mmfile(mmfile_t *ptr, const char *filename)
-Peter
-
To unsubscribe from this list: send the line "unsubscribe git" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
