From: Phillip Wood Date: Tue, 20 Jan 2026 16:32:54 GMT Subject: Re: [PATCH 07/10] xdiff: replace xdfile_t.dstart with xdfenv_t.delta_start Message-ID: In-Reply-To: On 02/01/2026 18:52, Ezekiel Newren via GitGitGadget wrote: > From: Ezekiel Newren > > Placing delta_start in xdfenv_t instead of xdfile_t provides a more > appropriate context since this variable only makes sense with a pair > of files. View with --color-words. So as dstart and dend must be the same for both files we now store the values once in xdfenv_t. That explains why we start passing xdfenv_t around rather than xdfile_t in patch 5. Thanks Phillip > Signed-off-by: Ezekiel Newren > --- > xdiff/xhistogram.c | 4 ++-- > xdiff/xpatience.c | 4 ++-- > xdiff/xprepare.c | 17 +++++++++-------- > xdiff/xtypes.h | 3 ++- > 4 files changed, 15 insertions(+), 13 deletions(-) > > diff --git a/xdiff/xhistogram.c b/xdiff/xhistogram.c > index 5ae1282c27..eb6a52d9ba 100644 > --- a/xdiff/xhistogram.c > +++ b/xdiff/xhistogram.c > @@ -365,6 +365,6 @@ out: > int xdl_do_histogram_diff(xpparam_t const *xpp, xdfenv_t *env) > { > return histogram_diff(xpp, env, > - env->xdf1.dstart + 1, env->xdf1.dend - env->xdf1.dstart + 1, > - env->xdf2.dstart + 1, env->xdf2.dend - env->xdf2.dstart + 1); > + env->delta_start + 1, env->xdf1.dend - env->delta_start + 1, > + env->delta_start + 1, env->xdf2.dend - env->delta_start + 1); > } > diff --git a/xdiff/xpatience.c b/xdiff/xpatience.c > index 2bce07cf48..bd0ffbb417 100644 > --- a/xdiff/xpatience.c > +++ b/xdiff/xpatience.c > @@ -374,6 +374,6 @@ static int patience_diff(xpparam_t const *xpp, xdfenv_t *env, > int xdl_do_patience_diff(xpparam_t const *xpp, xdfenv_t *env) > { > return patience_diff(xpp, env, > - env->xdf1.dstart + 1, env->xdf1.dend - env->xdf1.dstart + 1, > - env->xdf2.dstart + 1, env->xdf2.dend - env->xdf2.dstart + 1); > + env->delta_start + 1, env->xdf1.dend - env->delta_start + 1, > + env->delta_start + 1, env->xdf2.dend - env->delta_start + 1); > } > diff --git a/xdiff/xprepare.c b/xdiff/xprepare.c > index 06b6a6f804..e88468e74c 100644 > --- a/xdiff/xprepare.c > +++ b/xdiff/xprepare.c > @@ -173,7 +173,6 @@ static int xdl_prepare_ctx(mmfile_t *mf, xdfile_t *xdf, uint64_t flags) { > > xdf->changed += 1; > xdf->nreff = 0; > - xdf->dstart = 0; > xdf->dend = xdf->nrec - 1; > > return 0; > @@ -287,7 +286,7 @@ static int xdl_cleanup_records(xdlclassifier_t *cf, xdfenv_t *xe) { > */ > if ((mlim = xdl_bogosqrt((long)xe->xdf1.nrec)) > XDL_MAX_EQLIMIT) > mlim = XDL_MAX_EQLIMIT; > - for (i = xe->xdf1.dstart, recs = &xe->xdf1.recs[xe->xdf1.dstart]; i <= xe->xdf1.dend; i++, recs++) { > + for (i = xe->delta_start, recs = &xe->xdf1.recs[xe->delta_start]; i <= xe->xdf1.dend; i++, recs++) { > rcrec = cf->rcrecs[recs->minimal_perfect_hash]; > nm = rcrec ? rcrec->len2 : 0; > action1[i] = (nm == 0) ? DISCARD: (nm >= mlim && !need_min) ? INVESTIGATE: KEEP; > @@ -295,7 +294,7 @@ static int xdl_cleanup_records(xdlclassifier_t *cf, xdfenv_t *xe) { > > if ((mlim = xdl_bogosqrt((long)xe->xdf2.nrec)) > XDL_MAX_EQLIMIT) > mlim = XDL_MAX_EQLIMIT; > - for (i = xe->xdf2.dstart, recs = &xe->xdf2.recs[xe->xdf2.dstart]; i <= xe->xdf2.dend; i++, recs++) { > + for (i = xe->delta_start, recs = &xe->xdf2.recs[xe->delta_start]; i <= xe->xdf2.dend; i++, recs++) { > rcrec = cf->rcrecs[recs->minimal_perfect_hash]; > nm = rcrec ? rcrec->len1 : 0; > action2[i] = (nm == 0) ? DISCARD: (nm >= mlim && !need_min) ? INVESTIGATE: KEEP; > @@ -306,10 +305,10 @@ static int xdl_cleanup_records(xdlclassifier_t *cf, xdfenv_t *xe) { > * false, or become true. > */ > xe->xdf1.nreff = 0; > - for (i = xe->xdf1.dstart, recs = &xe->xdf1.recs[xe->xdf1.dstart]; > + for (i = xe->delta_start, recs = &xe->xdf1.recs[xe->delta_start]; > i <= xe->xdf1.dend; i++, recs++) { > if (action1[i] == KEEP || > - (action1[i] == INVESTIGATE && !xdl_clean_mmatch(action1, i, xe->xdf1.dstart, xe->xdf1.dend))) { > + (action1[i] == INVESTIGATE && !xdl_clean_mmatch(action1, i, xe->delta_start, xe->xdf1.dend))) { > xe->xdf1.reference_index[xe->xdf1.nreff++] = i; > /* changed[i] remains false, i.e. keep */ > } else > @@ -318,10 +317,10 @@ static int xdl_cleanup_records(xdlclassifier_t *cf, xdfenv_t *xe) { > } > > xe->xdf2.nreff = 0; > - for (i = xe->xdf2.dstart, recs = &xe->xdf2.recs[xe->xdf2.dstart]; > + for (i = xe->delta_start, recs = &xe->xdf2.recs[xe->delta_start]; > i <= xe->xdf2.dend; i++, recs++) { > if (action2[i] == KEEP || > - (action2[i] == INVESTIGATE && !xdl_clean_mmatch(action2, i, xe->xdf2.dstart, xe->xdf2.dend))) { > + (action2[i] == INVESTIGATE && !xdl_clean_mmatch(action2, i, xe->delta_start, xe->xdf2.dend))) { > xe->xdf2.reference_index[xe->xdf2.nreff++] = i; > /* changed[i] remains false, i.e. keep */ > } else > @@ -348,7 +347,7 @@ static void xdl_trim_ends(xdfenv_t *xe) > size_t mph1 = xe->xdf1.recs[i].minimal_perfect_hash; > size_t mph2 = xe->xdf2.recs[i].minimal_perfect_hash; > if (mph1 != mph2) { > - xe->xdf1.dstart = xe->xdf2.dstart = (ssize_t)i; > + xe->delta_start = (ssize_t)i; > lim -= i; > break; > } > @@ -370,6 +369,8 @@ int xdl_prepare_env(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp, > xdfenv_t *xe) { > xdlclassifier_t cf; > > + xe->delta_start = 0; > + > if (xdl_prepare_ctx(mf1, &xe->xdf1, xpp->flags) < 0) { > > return -1; > diff --git a/xdiff/xtypes.h b/xdiff/xtypes.h > index 979586f20a..bda1f85eb0 100644 > --- a/xdiff/xtypes.h > +++ b/xdiff/xtypes.h > @@ -48,7 +48,7 @@ typedef struct s_xrecord { > typedef struct s_xdfile { > xrecord_t *recs; > size_t nrec; > - ptrdiff_t dstart, dend; > + ptrdiff_t dend; > bool *changed; > size_t *reference_index; > size_t nreff; > @@ -56,6 +56,7 @@ typedef struct s_xdfile { > > typedef struct s_xdfenv { > xdfile_t xdf1, xdf2; > + size_t delta_start; > } xdfenv_t; > >