EMACS_INT
buf_bytepos_to_charpos (struct buffer *b, EMACS_INT bytepos)
{
struct Lisp_Marker *tail;
EMACS_INT best_above, best_above_byte;
EMACS_INT best_below, best_below_byte;
if (bytepos < BUF_BEG_BYTE (b) || bytepos > BUF_Z_BYTE (b))
abort ();
best_above = BUF_Z (b);
best_above_byte = BUF_Z_BYTE (b);
/* If this buffer has as many characters as bytes,
each character must be one byte.
This takes care of the case where enable-multibyte-characters is nil. */
if (best_above == best_above_byte)
return bytepos;
best_below = BEG;
best_below_byte = BEG_BYTE;
CONSIDER (BUF_PT_BYTE (b), BUF_PT (b));
CONSIDER (BUF_GPT_BYTE (b), BUF_GPT (b));
CONSIDER (BUF_BEGV_BYTE (b), BUF_BEGV (b));
CONSIDER (BUF_ZV_BYTE (b), BUF_ZV (b));
if (b == cached_buffer && BUF_MODIFF (b) == cached_modiff)
CONSIDER (cached_bytepos, cached_charpos);
for (tail = BUF_MARKERS (b); tail; tail = tail->next)
{
CONSIDER (tail->bytepos, tail->charpos);
/* If we are down to a range of 50 chars,
don't bother checking any other markers;
scan the intervening chars directly now. */
if (best_above - best_below < 50)
break;
}
/* We get here if we did not exactly hit one of the known places.
We have one known above and one known below.
Scan, counting characters, from whichever one is closer. */
if (bytepos - best_below_byte < best_above_byte - bytepos)
{
int record = bytepos - best_below_byte > 5000;
while (best_below_byte < bytepos)
{
best_below++;
BUF_INC_POS (b, best_below_byte);
}
/* If this position is quite far from the nearest known position,
cache the correspondence by creating a marker here.
It will last until the next GC.
But don't do it if BUF_MARKERS is nil;
that is a signal from Fset_buffer_multibyte. */
if (record && BUF_MARKERS (b))
{
Lisp_Object marker, buffer;
marker = Fmake_marker ();
XSETBUFFER (buffer, b);
set_marker_both (marker, buffer, best_below, best_below_byte);
}
if (byte_debug_flag)
byte_char_debug_check (b, best_below, bytepos);
cached_buffer = b;
cached_modiff = BUF_MODIFF (b);
cached_charpos = best_below;
cached_bytepos = best_below_byte;
return best_below;
}
else
{
int record = best_above_byte - bytepos > 5000;
while (best_above_byte > bytepos)
{
best_above--;
BUF_DEC_POS (b, best_above_byte);
}
/* If this position is quite far from the nearest known position,
cache the correspondence by creating a marker here.
It will last until the next GC.
But don't do it if BUF_MARKERS is nil;
that is a signal from Fset_buffer_multibyte. */
if (record && BUF_MARKERS (b))
{
Lisp_Object marker, buffer;
marker = Fmake_marker ();
XSETBUFFER (buffer, b);
set_marker_both (marker, buffer, best_above, best_above_byte);
}
if (byte_debug_flag)
byte_char_debug_check (b, best_above, bytepos);
cached_buffer = b;
cached_modiff = BUF_MODIFF (b);
cached_charpos = best_above;
cached_bytepos = best_above_byte;
return best_above;
}
}
ptrdiff_t
buf_charpos_to_bytepos (struct buffer *b, ptrdiff_t charpos)
{
struct Lisp_Marker *tail;
ptrdiff_t best_above, best_above_byte;
ptrdiff_t best_below, best_below_byte;
eassert (BUF_BEG (b) <= charpos && charpos <= BUF_Z (b));
best_above = BUF_Z (b);
best_above_byte = BUF_Z_BYTE (b);
/* If this buffer has as many characters as bytes,
each character must be one byte.
This takes care of the case where enable-multibyte-characters is nil. */
if (best_above == best_above_byte)
return charpos;
best_below = BEG;
best_below_byte = BEG_BYTE;
/* We find in best_above and best_above_byte
the closest known point above CHARPOS,
and in best_below and best_below_byte
the closest known point below CHARPOS,
If at any point we can tell that the space between those
two best approximations is all single-byte,
we interpolate the result immediately. */
CONSIDER (BUF_PT (b), BUF_PT_BYTE (b));
CONSIDER (BUF_GPT (b), BUF_GPT_BYTE (b));
CONSIDER (BUF_BEGV (b), BUF_BEGV_BYTE (b));
CONSIDER (BUF_ZV (b), BUF_ZV_BYTE (b));
if (b == cached_buffer && BUF_MODIFF (b) == cached_modiff)
CONSIDER (cached_charpos, cached_bytepos);
for (tail = BUF_MARKERS (b); tail; tail = tail->next)
{
CONSIDER (tail->charpos, tail->bytepos);
/* If we are down to a range of 50 chars,
don't bother checking any other markers;
scan the intervening chars directly now. */
if (best_above - best_below < 50)
break;
}
/* We get here if we did not exactly hit one of the known places.
We have one known above and one known below.
Scan, counting characters, from whichever one is closer. */
if (charpos - best_below < best_above - charpos)
{
bool record = charpos - best_below > 5000;
while (best_below != charpos)
{
best_below++;
BUF_INC_POS (b, best_below_byte);
}
/* If this position is quite far from the nearest known position,
cache the correspondence by creating a marker here.
It will last until the next GC. */
if (record)
build_marker (b, best_below, best_below_byte);
byte_char_debug_check (b, best_below, best_below_byte);
cached_buffer = b;
cached_modiff = BUF_MODIFF (b);
cached_charpos = best_below;
cached_bytepos = best_below_byte;
return best_below_byte;
}
else
{
bool record = best_above - charpos > 5000;
while (best_above != charpos)
{
best_above--;
BUF_DEC_POS (b, best_above_byte);
}
/* If this position is quite far from the nearest known position,
cache the correspondence by creating a marker here.
It will last until the next GC. */
if (record)
build_marker (b, best_above, best_above_byte);
byte_char_debug_check (b, best_above, best_above_byte);
cached_buffer = b;
cached_modiff = BUF_MODIFF (b);
cached_charpos = best_above;
cached_bytepos = best_above_byte;
return best_above_byte;
}
}
