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/* Calculate what line insertion or deletion to do, and do it
Copyright (C) 1985-1986, 1990, 1993-1994, 2001-2024 Free Software
Foundation, Inc.
This file is part of GNU Emacs.
GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.
GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>. */
#include <config.h>
/* The entire file is defined out under Android, where there is no
text terminal support of any kind. */
#ifndef HAVE_ANDROID
#include "lisp.h"
#include "termchar.h"
#include "dispextern.h"
#include "frame.h"
#include "termhooks.h"
struct matrix_elt
{
/* Cost of outputting through this line
if no insert/delete is done just above it. */
int writecost;
/* Cost of outputting through this line
if an insert is done just above it. */
int insertcost;
/* Cost of outputting through this line
if a delete is done just above it. */
int deletecost;
/* Number of inserts so far in this run of inserts,
for the cost in insertcost. */
int insertcount;
/* Number of deletes so far in this run of deletes,
for the cost in deletecost. */
int deletecount;
/* Number of writes so far since the last insert
or delete for the cost in writecost. */
int writecount;
};
static void do_direct_scrolling (struct frame *,
struct glyph_matrix *,
struct matrix_elt *,
int, int);
static void do_scrolling (struct frame *,
struct glyph_matrix *,
struct matrix_elt *,
int, int);
/* Determine, in matrix[i,j], the cost of updating the first j old
lines into the first i new lines using the general scrolling method.
This involves using insert or delete somewhere if i != j.
For each matrix elements, three kinds of costs are recorded:
the smallest cost that ends with an insert, the smallest
cost that ends with a delete, and the smallest cost that
ends with neither one. These are kept separate because
on some terminals the cost of doing an insert varies
depending on whether one was just done, etc. */
/* draw_cost[VPOS] is the cost of outputting new line at VPOS.
old_hash[VPOS] is the hash code of the old line at VPOS.
new_hash[VPOS] is the hash code of the new line at VPOS.
Note that these are not true frame vpos's, but relative
to the place at which the first mismatch between old and
new contents appears. */
static void
calculate_scrolling (struct frame *frame,
/* matrix is of size window_size + 1 on each side. */
struct matrix_elt *matrix,
int window_size, int lines_below,
int *draw_cost, unsigned *old_hash, unsigned *new_hash,
int free_at_end)
{
int i, j;
int frame_total_lines = FRAME_TOTAL_LINES (frame);
struct matrix_elt *p, *p1;
int cost, cost1;
int lines_moved = window_size
+ (FRAME_SCROLL_REGION_OK (frame) ? 0 : lines_below);
/* first_insert_cost[I] is the cost of doing the first insert-line
at the i'th line of the lines we are considering,
where I is origin 1 (as it is below). */
int *first_insert_cost
= &FRAME_INSERT_COST (frame)[frame_total_lines - 1 - lines_moved];
int *first_delete_cost
= &FRAME_DELETE_COST (frame)[frame_total_lines - 1 - lines_moved];
int *next_insert_cost
= &FRAME_INSERTN_COST (frame)[frame_total_lines - 1 - lines_moved];
int *next_delete_cost
= &FRAME_DELETEN_COST (frame)[frame_total_lines - 1 - lines_moved];
/* Discourage long scrolls on fast lines.
Don't scroll nearly a full frame height unless it saves
at least 1/4 second. */
int extra_cost
= clip_to_bounds (1, baud_rate / (10 * 4) / frame_total_lines, INT_MAX / 2);
/* initialize the top left corner of the matrix */
matrix->writecost = 0;
matrix->insertcost = SCROLL_INFINITY;
matrix->deletecost = SCROLL_INFINITY;
matrix->insertcount = 0;
matrix->deletecount = 0;
/* initialize the left edge of the matrix */
cost = first_insert_cost[1] - next_insert_cost[1];
for (i = 1; i <= window_size; i++)
{
p = matrix + i * (window_size + 1);
cost += draw_cost[i] + next_insert_cost[i] + extra_cost;
p->insertcost = cost;
p->writecost = SCROLL_INFINITY;
p->deletecost = SCROLL_INFINITY;
p->insertcount = i;
p->deletecount = 0;
}
/* initialize the top edge of the matrix */
cost = first_delete_cost[1] - next_delete_cost[1];
for (j = 1; j <= window_size; j++)
{
cost += next_delete_cost[j];
matrix[j].deletecost = cost;
matrix[j].writecost = SCROLL_INFINITY;
matrix[j].insertcost = SCROLL_INFINITY;
matrix[j].deletecount = j;
matrix[j].insertcount = 0;
}
/* `i' represents the vpos among new frame contents.
`j' represents the vpos among the old frame contents. */
p = matrix + window_size + 2; /* matrix [1, 1] */
for (i = 1; i <= window_size; i++, p++)
for (j = 1; j <= window_size; j++, p++)
{
/* p contains the address of matrix [i, j] */
/* First calculate the cost assuming we do
not insert or delete above this line.
That is, if we update through line i-1
based on old lines through j-1,
and then just change old line j to new line i. */
p1 = p - window_size - 2; /* matrix [i-1, j-1] */
cost = p1->writecost;
if (cost > p1->insertcost)
cost = p1->insertcost;
if (cost > p1->deletecost)
cost = p1->deletecost;
if (old_hash[j] != new_hash[i])
cost += draw_cost[i];
p->writecost = cost;
/* Calculate the cost if we do an insert-line
before outputting this line.
That is, we update through line i-1
based on old lines through j,
do an insert-line on line i,
and then output line i from scratch,
leaving old lines starting from j for reuse below. */
p1 = p - window_size - 1; /* matrix [i-1, j] */
/* No need to think about doing a delete followed
immediately by an insert. It cannot be as good
as not doing either of them. */
if (free_at_end == i)
{
cost = p1->writecost;
cost1 = p1->insertcost;
}
else
{
cost = p1->writecost + first_insert_cost[i];
if (p1->insertcount > i)
emacs_abort ();
cost1 = p1->insertcost + next_insert_cost[i - p1->insertcount];
}
p->insertcost = min (cost, cost1) + draw_cost[i] + extra_cost;
p->insertcount = (cost < cost1) ? 1 : p1->insertcount + 1;
if (p->insertcount > i)
emacs_abort ();
/* Calculate the cost if we do a delete line after
outputting this line.
That is, we update through line i
based on old lines through j-1,
and throw away old line j. */
p1 = p - 1; /* matrix [i, j-1] */
/* No need to think about doing an insert followed
immediately by a delete. */
if (free_at_end == i)
{
cost = p1->writecost;
cost1 = p1->deletecost;
}
else
{
cost = p1->writecost + first_delete_cost[i];
cost1 = p1->deletecost + next_delete_cost[i];
}
p->deletecost = min (cost, cost1);
p->deletecount = (cost < cost1) ? 1 : p1->deletecount + 1;
}
}
/* Perform insert-lines and delete-lines operations on CURRENT_MATRIX
according to the costs in MATRIX, using the general scrolling
method that is used if the terminal does not support the setting of
scroll windows (scroll_region_ok == 0).
WINDOW_SIZE is the number of lines being considered for scrolling
and UNCHANGED_AT_TOP is the vpos of the first line being
considered. These two arguments can specify any contiguous range
of lines. */
static void
do_scrolling (struct frame *frame, struct glyph_matrix *current_matrix,
struct matrix_elt *matrix, int window_size,
int unchanged_at_top)
{
struct matrix_elt *p;
int i, j, k;
USE_SAFE_ALLOCA;
/* True if we have set a terminal window with set_terminal_window. */
bool terminal_window_p = 0;
/* A queue for line insertions to be done. */
struct queue { int count, pos; };
struct queue *queue_start;
SAFE_NALLOCA (queue_start, 1, current_matrix->nrows);
struct queue *queue = queue_start;
char *retained_p = SAFE_ALLOCA (window_size);
int *copy_from;
SAFE_NALLOCA (copy_from, 1, window_size);
/* Zero means line is empty. */
memset (retained_p, 0, window_size * sizeof (char));
for (k = 0; k < window_size; ++k)
copy_from[k] = -1;
#ifdef GLYPH_DEBUG
# define CHECK_BOUNDS \
do \
{ \
int ck; \
for (ck = 0; ck < window_size; ++ck) \
eassert (copy_from[ck] == -1 \
|| (copy_from[ck] >= 0 && copy_from[ck] < window_size)); \
} \
while (0);
#endif
/* When j is advanced, this corresponds to deleted lines.
When i is advanced, this corresponds to inserted lines. */
i = j = window_size;
while (i > 0 || j > 0)
{
p = matrix + i * (window_size + 1) + j;
if (p->insertcost < p->writecost && p->insertcost < p->deletecost)
{
/* Insert should be done at vpos i-1, plus maybe some before.
Queue the screen operation to be performed. */
queue->count = p->insertcount;
queue->pos = i + unchanged_at_top - p->insertcount;
++queue;
/* By incrementing I, we leave room in the result rows
for the empty rows opened up. */
i -= p->insertcount;
}
else if (p->deletecost < p->writecost)
{
/* Old line at vpos j-1, and maybe some before it, should be
deleted. By decrementing J, we skip some lines in the
temp_rows which is equivalent to omitting these lines in
the result rows, thus deleting them. */
j -= p->deletecount;
/* Set the terminal window, if not done already. */
if (! terminal_window_p)
{
set_terminal_window (frame, window_size + unchanged_at_top);
terminal_window_p = 1;
}
/* Delete lines on the terminal. */
ins_del_lines (frame, j + unchanged_at_top, - p->deletecount);
}
else
{
/* Best thing done here is no insert or delete, i.e. a write. */
--i, --j;
eassert (i >= 0 && i < window_size);
eassert (j >= 0 && j < window_size);
copy_from[i] = j;
retained_p[j] = 1;
#ifdef GLYPH_DEBUG
CHECK_BOUNDS;
#endif
}
}
/* Now do all insertions queued above. */
if (queue > queue_start)
{
int next = -1;
/* Set the terminal window if not yet done. */
if (!terminal_window_p)
{
set_terminal_window (frame, window_size + unchanged_at_top);
terminal_window_p = 1;
}
do
{
--queue;
/* Do the deletion on the terminal. */
ins_del_lines (frame, queue->pos, queue->count);
/* All lines in the range deleted become empty in the glyph
matrix. Assign to them glyph rows that are not retained.
K is the starting position of the deleted range relative
to the window we are working in. */
k = queue->pos - unchanged_at_top;
for (j = 0; j < queue->count; ++j)
{
/* Find the next row not retained. */
while (retained_p[++next])
;
/* Record that this row is to be used for the empty
glyph row j. */
copy_from[k + j] = next;
}
}
while (queue > queue_start);
}
for (k = 0; k < window_size; ++k)
eassert (copy_from[k] >= 0 && copy_from[k] < window_size);
/* Perform the row swizzling. */
mirrored_line_dance (current_matrix, unchanged_at_top, window_size,
copy_from, retained_p);
/* Some sanity checks if GLYPH_DEBUG is defined. */
CHECK_MATRIX (current_matrix);
if (terminal_window_p)
set_terminal_window (frame, 0);
SAFE_FREE ();
}
/* Determine, in matrix[i,j], the cost of updating the first j
old lines into the first i new lines using the direct
scrolling method. When the old line and the new line have
different hash codes, the calculated cost of updating old
line j into new line i includes the cost of outputting new
line i, and if i != j, the cost of outputting the old line j
is also included, as a penalty for moving the line and then
erasing it. In addition, the cost of updating a sequence of
lines with constant i - j includes the cost of scrolling the
old lines into their new positions, unless i == j. Scrolling
is achieved by setting the screen window to avoid affecting
other lines below, and inserting or deleting lines at the top
of the scrolled region. The cost of scrolling a sequence of
lines includes the fixed cost of specifying a scroll region,
plus a variable cost which can depend upon the number of lines
involved and the distance by which they are scrolled, and an
extra cost to discourage long scrolls.
As reflected in the matrix, an insert or delete does not
correspond directly to the insertion or deletion which is
used in scrolling lines. An insert means that the value of i
has increased without a corresponding increase in the value
of j. A delete means that the value of j has increased
without a corresponding increase in the value of i. A write
means that i and j are both increased by the same amount, and
that the old lines will be moved to their new positions.
An insert following a delete is allowed only if i > j.
A delete following an insert is allowed only if i < j.
These restrictions ensure that the new lines in an insert
will always be blank as an effect of the neighboring writes.
Thus the calculated cost of an insert is simply the cost of
outputting the new line contents. The direct cost of a
delete is zero. Inserts and deletes indirectly affect the
total cost through their influence on subsequent writes. */
/* The vectors draw_cost, old_hash, and new_hash have the same
meanings here as in calculate_scrolling, and old_draw_cost
is the equivalent of draw_cost for the old line contents */
static void
calculate_direct_scrolling (struct frame *frame,
/* matrix is of size window_size + 1 on each side. */
struct matrix_elt *matrix,
int window_size, int lines_below,
int *draw_cost, int *old_draw_cost,
unsigned *old_hash, unsigned *new_hash,
int free_at_end)
{
int i, j;
int frame_total_lines = FRAME_TOTAL_LINES (frame);
struct matrix_elt *p, *p1;
int cost, cost1, delta;
/* first_insert_cost[-I] is the cost of doing the first insert-line
at a position I lines above the bottom line in the scroll window. */
int *first_insert_cost
= &FRAME_INSERT_COST (frame)[frame_total_lines - 1];
int *first_delete_cost
= &FRAME_DELETE_COST (frame)[frame_total_lines - 1];
int *next_insert_cost
= &FRAME_INSERTN_COST (frame)[frame_total_lines - 1];
int *next_delete_cost
= &FRAME_DELETEN_COST (frame)[frame_total_lines - 1];
int scroll_overhead;
/* Discourage long scrolls on fast lines.
Don't scroll nearly a full frame height unless it saves
at least 1/4 second. */
int extra_cost
= clip_to_bounds (1, baud_rate / (10 * 4) / frame_total_lines, INT_MAX / 2);
/* Overhead of setting the scroll window, plus the extra
cost of scrolling by a distance of one. The extra cost is
added once for consistency with the cost vectors */
scroll_overhead
= FRAME_SCROLL_REGION_COST (frame) + extra_cost;
/* initialize the top left corner of the matrix */
matrix->writecost = 0;
matrix->insertcost = SCROLL_INFINITY;
matrix->deletecost = SCROLL_INFINITY;
matrix->writecount = 0;
matrix->insertcount = 0;
matrix->deletecount = 0;
/* initialize the left edge of the matrix */
cost = 0;
for (i = 1; i <= window_size; i++)
{
p = matrix + i * (window_size + 1);
cost += draw_cost[i];
p->insertcost = cost;
p->writecost = SCROLL_INFINITY;
p->deletecost = SCROLL_INFINITY;
p->insertcount = i;
p->writecount = 0;
p->deletecount = 0;
}
/* initialize the top edge of the matrix */
for (j = 1; j <= window_size; j++)
{
matrix[j].deletecost = 0;
matrix[j].writecost = SCROLL_INFINITY;
matrix[j].insertcost = SCROLL_INFINITY;
matrix[j].deletecount = j;
matrix[j].writecount = 0;
matrix[j].insertcount = 0;
}
/* `i' represents the vpos among new frame contents.
`j' represents the vpos among the old frame contents. */
p = matrix + window_size + 2; /* matrix [1, 1] */
for (i = 1; i <= window_size; i++, p++)
for (j = 1; j <= window_size; j++, p++)
{
/* p contains the address of matrix [i, j] */
/* First calculate the cost assuming we do
not insert or delete above this line.
That is, if we update through line i-1
based on old lines through j-1,
and then just change old line j to new line i.
Depending on which choice gives the lower cost,
this usually involves either scrolling a single line
or extending a sequence of scrolled lines, but
when i == j, no scrolling is required. */
p1 = p - window_size - 2; /* matrix [i-1, j-1] */
cost = p1->insertcost;
if (cost > p1->deletecost)
cost = p1->deletecost;
cost1 = p1->writecost;
if (i == j)
{
if (cost > cost1)
{
cost = cost1;
p->writecount = p1->writecount + 1;
}
else
p->writecount = 1;
if (old_hash[j] != new_hash[i])
{
cost += draw_cost[i];
}
}
else
{
if (i > j)
{
delta = i - j;
/* The cost added here for scrolling the first line by
a distance N includes the overhead of setting the
scroll window, the cost of inserting N lines at a
position N lines above the bottom line of the window,
and an extra cost which is proportional to N. */
cost += scroll_overhead + first_insert_cost[-delta] +
(delta-1) * (next_insert_cost[-delta] + extra_cost);
/* In the most general case, the insertion overhead and
the multiply factor can grow linearly as the distance
from the bottom of the window increases. The incremental
cost of scrolling an additional line depends upon the
rate of change of these two parameters. Each of these
growth rates can be determined by a simple difference.
To reduce the cumulative effects of rounding error, we
vary the position at which the difference is computed. */
cost1 += first_insert_cost[-j] - first_insert_cost[1-j] +
(delta-1) * (next_insert_cost[-j] - next_insert_cost[1-j]);
}
else
{
delta = j - i;
cost += scroll_overhead + first_delete_cost[-delta] +
(delta-1) * (next_delete_cost[-delta] + extra_cost);
cost1 += first_delete_cost[-i] - first_delete_cost[1-i] +
(delta-1) * ( next_delete_cost[-i] - next_delete_cost[1-i]);
}
if (cost1 < cost)
{
cost = cost1;
p->writecount = p1->writecount + 1;
}
else
p->writecount = 1;
if (old_hash[j] != new_hash[i])
{
cost += draw_cost[i] + old_draw_cost[j];
}
}
p->writecost = cost;
/* Calculate the cost if we do an insert-line
before outputting this line.
That is, we update through line i-1
based on old lines through j,
do an insert-line on line i,
and then output line i from scratch,
leaving old lines starting from j for reuse below. */
p1 = p - window_size - 1; /* matrix [i-1, j] */
cost = p1->writecost;
/* If i > j, an insert is allowed after a delete. */
if (i > j && p1->deletecost < cost)
cost = p1->deletecost;
if (p1->insertcost <= cost)
{
cost = p1->insertcost;
p->insertcount = p1->insertcount + 1;
}
else
p->insertcount = 1;
cost += draw_cost[i];
p->insertcost = cost;
/* Calculate the cost if we do a delete line after
outputting this line.
That is, we update through line i
based on old lines through j-1,
and throw away old line j. */
p1 = p - 1; /* matrix [i, j-1] */
cost = p1->writecost;
/* If i < j, a delete is allowed after an insert. */
if (i < j && p1->insertcost < cost)
cost = p1->insertcost;
cost1 = p1->deletecost;
if (p1->deletecost <= cost)
{
cost = p1->deletecost;
p->deletecount = p1->deletecount + 1;
}
else
p->deletecount = 1;
p->deletecost = cost;
}
}
/* Perform insert-lines and delete-lines operations on CURRENT_MATRIX
according to the costs in MATRIX, using the direct scrolling method
which is used when the terminal supports setting a scroll window
(scroll_region_ok).
WINDOW_SIZE is the number of lines being considered for scrolling
and UNCHANGED_AT_TOP is the vpos of the first line being
considered. These two arguments can specify any contiguous range
of lines.
In the direct scrolling method, a new scroll window is selected
before each insertion or deletion, so that groups of lines can be
scrolled directly to their final vertical positions. This method
is described in more detail in calculate_direct_scrolling, where
the cost matrix for this approach is constructed. */
static void
do_direct_scrolling (struct frame *frame, struct glyph_matrix *current_matrix,
struct matrix_elt *cost_matrix, int window_size,
int unchanged_at_top)
{
struct matrix_elt *p;
int i, j;
USE_SAFE_ALLOCA;
/* A queue of deletions and insertions to be performed. */
struct alt_queue { int count, pos, window; };
struct alt_queue *queue_start;
SAFE_NALLOCA (queue_start, 1, window_size);
struct alt_queue *queue = queue_start;
/* True if a terminal window has been set with set_terminal_window. */
bool terminal_window_p = 0;
/* If true, a write has been selected, allowing either an insert or a
delete to be selected next. If false, a delete cannot be selected
unless j < i, and an insert cannot be selected unless i < j.
This corresponds to a similar restriction (with the ordering
reversed) in calculate_direct_scrolling, which is intended to
ensure that lines marked as inserted will be blank. */
bool write_follows_p = 1;
/* For each row in the new matrix what row of the old matrix it is. */
int *copy_from;
SAFE_NALLOCA (copy_from, 1, window_size);
/* Non-zero for each row in the new matrix that is retained from the
old matrix. Lines not retained are empty. */
char *retained_p = SAFE_ALLOCA (window_size);
memset (retained_p, 0, window_size * sizeof (char));
/* Perform some sanity checks when GLYPH_DEBUG is on. */
CHECK_MATRIX (current_matrix);
/* We are working on the line range UNCHANGED_AT_TOP ...
UNCHANGED_AT_TOP + WINDOW_SIZE (not including) in CURRENT_MATRIX.
We step through lines in this range from the end to the start. I
is an index into new lines, j an index into old lines. The cost
matrix determines what to do for ranges of indices.
If i is decremented without also decrementing j, this corresponds
to inserting empty lines in the result. If j is decremented
without also decrementing i, this corresponds to omitting these
lines in the new rows, i.e. rows are deleted. */
i = j = window_size;
while (i > 0 || j > 0)
{
p = cost_matrix + i * (window_size + 1) + j;
if (p->insertcost < p->writecost
&& p->insertcost < p->deletecost
&& (write_follows_p || i < j))
{
/* Insert is cheaper than deleting or writing lines. Leave
a hole in the result display that will be filled with
empty lines when the queue is emptied. */
queue->count = 0;
queue->window = i;
queue->pos = i - p->insertcount;
++queue;
i -= p->insertcount;
write_follows_p = 0;
}
else if (p->deletecost < p->writecost
&& (write_follows_p || i > j))
{
/* Deleting lines is cheaper. By decrementing J, omit
deletecount lines from the original. */
write_follows_p = 0;
j -= p->deletecount;
}
else
{
/* One or more lines should be written. In the direct
scrolling method we do this by scrolling the lines to the
place they belong. */
int n_to_write = p->writecount;
write_follows_p = 1;
eassert (n_to_write > 0);
if (i > j)
{
/* Immediately insert lines */
set_terminal_window (frame, i + unchanged_at_top);
terminal_window_p = 1;
ins_del_lines (frame, j - n_to_write + unchanged_at_top, i - j);
}
else if (i < j)
{
/* Queue the deletion of a group of lines */
queue->pos = i - n_to_write + unchanged_at_top;
queue->window = j + unchanged_at_top;
queue->count = i - j;
++queue;
}
while (n_to_write > 0)
{
--i, --j, --n_to_write;
copy_from[i] = j;
retained_p[j] = 1;
}
}
}
/* Do queued operations. */
if (queue > queue_start)
{
int next = -1;
do
{
--queue;
if (queue->count)
{
set_terminal_window (frame, queue->window);
terminal_window_p = 1;
ins_del_lines (frame, queue->pos, queue->count);
}
else
{
for (j = queue->window - 1; j >= queue->pos; --j)
{
while (retained_p[++next])
;
copy_from[j] = next;
}
}
}
while (queue > queue_start);
}
/* Now, for each row I in the range of rows we are working on,
copy_from[i] gives the original line to copy to I, and
retained_p[copy_from[i]] is zero if line I in the new display is
empty. */
mirrored_line_dance (current_matrix, unchanged_at_top, window_size,
copy_from, retained_p);
if (terminal_window_p)
set_terminal_window (frame, 0);
SAFE_FREE ();
}
void
scrolling_1 (struct frame *frame, int window_size, int unchanged_at_top,
int unchanged_at_bottom, int *draw_cost, int *old_draw_cost,
unsigned *old_hash, unsigned *new_hash, int free_at_end)
{
USE_SAFE_ALLOCA;
struct matrix_elt *matrix;
SAFE_NALLOCA (matrix, window_size + 1, window_size + 1);
if (FRAME_SCROLL_REGION_OK (frame))
{
calculate_direct_scrolling (frame, matrix, window_size,
unchanged_at_bottom,
draw_cost, old_draw_cost,
old_hash, new_hash, free_at_end);
do_direct_scrolling (frame, frame->current_matrix,
matrix, window_size, unchanged_at_top);
}
else
{
calculate_scrolling (frame, matrix, window_size, unchanged_at_bottom,
draw_cost, old_hash, new_hash,
free_at_end);
do_scrolling (frame,
frame->current_matrix, matrix, window_size,
unchanged_at_top);
}
SAFE_FREE ();
}
/* Return number of lines in common between current and desired frame
contents described to us only as vectors of hash codes OLDHASH and
NEWHASH. Consider only vpos range START to END (not including
END). Ignore short lines on the assumption that avoiding redrawing
such a line will have little weight. */
int
scrolling_max_lines_saved (int start, int end,
unsigned *oldhash, unsigned *newhash,
int *cost)
{
enum { LOG2_NLINES = 9 };
enum { NLINES = 1 << LOG2_NLINES };
struct { unsigned hash; int count; } lines[NLINES];
int i, h;
int matchcount = 0;
int avg_length = 0;
int threshold;
/* Compute a threshold which is 1/4 of average length of these lines. */
for (i = start; i < end; i++)
avg_length += cost[i];
avg_length /= end - start;
threshold = avg_length / 4;
memset (lines, 0, sizeof lines);
/* Put new lines' hash codes in hash table. Ignore lines shorter
than the threshold. Thus, if the lines that are in common are
mainly the ones that are short, they won't count. */
for (i = start; i < end; i++)
{
if (cost[i] > threshold)
{
h = newhash[i] & (NLINES - 1);
lines[h].hash = newhash[i];
lines[h].count++;
}
}
/* Look up old line hash codes in the hash table. Count number of
matches between old lines and new. */
for (i = start; i < end; i++)
{
h = oldhash[i] & (NLINES - 1);
if (oldhash[i] == lines[h].hash)
{
matchcount++;
if (--lines[h].count == 0)
lines[h].hash = 0;
}
}
return matchcount;
}
/* Calculate the line insertion/deletion
overhead and multiply factor values */
static void
line_ins_del (struct frame *frame, int ov1, int pf1, int ovn, int pfn,
int *ov, int *mf)
{
int i;
int frame_total_lines = FRAME_TOTAL_LINES (frame);
int insert_overhead = ov1 * 10;
int next_insert_cost = ovn * 10;
for (i = frame_total_lines - 1; i >= 0; i--)
{
mf[i] = next_insert_cost / 10;
next_insert_cost += pfn;
ov[i] = (insert_overhead + next_insert_cost) / 10;
insert_overhead += pf1;
}
}
static void
ins_del_costs (struct frame *frame,
const char *one_line_string, const char *multi_string,
const char *setup_string, const char *cleanup_string,
int *costvec, int *ncostvec,
int coefficient)
{
if (multi_string)
line_ins_del (frame,
string_cost (multi_string) * coefficient,
per_line_cost (multi_string) * coefficient,
0, 0, costvec, ncostvec);
else if (one_line_string)
line_ins_del (frame,
string_cost (setup_string) + string_cost (cleanup_string), 0,
string_cost (one_line_string),
per_line_cost (one_line_string),
costvec, ncostvec);
else
line_ins_del (frame,
9999, 0, 9999, 0,
costvec, ncostvec);
}
/* Calculate the insert and delete line costs.
Note that this is done even when running with a window system
because we want to know how long scrolling takes (and avoid it).
This must be redone whenever the frame height changes.
We keep the ID costs in a precomputed array based on the position
at which the I or D is performed. Also, there are two kinds of ID
costs: the "once-only" and the "repeated". This is to handle both
those terminals that are able to insert N lines at a time (once-
only) and those that must repeatedly insert one line.
The cost to insert N lines at line L is
[tt.t_ILov + (frame_total_lines + 1 - L) * tt.t_ILpf] +
N * [tt.t_ILnov + (frame_total_lines + 1 - L) * tt.t_ILnpf]
ILov represents the basic insert line overhead. ILpf is the padding
required to allow the terminal time to move a line: insertion at line
L changes (frame_total_lines + 1 - L) lines.
The first bracketed expression above is the overhead; the second is
the multiply factor. Both are dependent only on the position at
which the insert is performed. We store the overhead in
FRAME_INSERT_COST (frame) and the multiply factor in
FRAME_INSERTN_COST (frame). Note however that any insertion
must include at least one multiply factor. Rather than compute this
as FRAME_INSERT_COST (frame)[line]+FRAME_INSERTN_COST (frame)[line],
we add FRAME_INSERTN_COST (frame) into FRAME_INSERT_COST (frame).
This is reasonable because of the particular algorithm used in calcM.
Deletion is essentially the same as insertion.
*/
void
do_line_insertion_deletion_costs (struct frame *frame,
const char *ins_line_string,
const char *multi_ins_string,
const char *del_line_string,
const char *multi_del_string,
const char *setup_string,
const char *cleanup_string,
int coefficient)
{
int frame_total_lines = FRAME_TOTAL_LINES (frame);
FRAME_INSERT_COST (frame) =
xnrealloc (FRAME_INSERT_COST (frame), frame_total_lines, sizeof (int));
FRAME_DELETEN_COST (frame) =
xnrealloc (FRAME_DELETEN_COST (frame), frame_total_lines, sizeof (int));
FRAME_INSERTN_COST (frame) =
xnrealloc (FRAME_INSERTN_COST (frame), frame_total_lines, sizeof (int));
FRAME_DELETE_COST (frame) =
xnrealloc (FRAME_DELETE_COST (frame), frame_total_lines, sizeof (int));
ins_del_costs (frame,
ins_line_string, multi_ins_string,
setup_string, cleanup_string,
FRAME_INSERT_COST (frame), FRAME_INSERTN_COST (frame),
coefficient);
ins_del_costs (frame,
del_line_string, multi_del_string,
setup_string, cleanup_string,
FRAME_DELETE_COST (frame), FRAME_DELETEN_COST (frame),
coefficient);
}
#endif
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