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Mikael Djurfeldt 1998-10-30 08:25:05 +00:00
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1998-10-29 Mikael Djurfeldt <mdj@barbara.nada.kth.se>
This change adds the ability to use `unread-char' multiple times
without interspersed reads and adds the new procedure
`unread-string'. The change is optimized for the common case of
unreading a single character. This is also the reason behind the
choice to store characters in the port itself: in most cases no
extra malloc is required.
The amount of code in some macros in ports.h has been increased to
the extent that they would fit better as C functions, but, since
this code belongs to the port representation, such functions
should be placed in ports.c which would cause calls back and forth
between ports.c and genio.c. That is not good for performance.
Also, keeping them as macros allows the compiler to do some
optimizations which are needed to make the current interface
(SCM_CRDYP, SCM_CGETUN, SCM_TRY_CLRDY) efficient.
One benchmark (Guile startup time) indicates an increase of
loading speed of 1%. Another (reading (using `read') boot-9.scm
10 times) shows no change in performance.
(Caveat: Since Gary is redesigning I/O anyway, no big efforts were
made to find a beautiful solution.)
* ports.h (SCM_CLRDY, SCM_CUNGET, SCM_CGETUN): Rewritten.
(SCM_TRY_CLRDY): New macro: Only clear the first unread
character. (SCM_CLRDY clears all.)
(SCM_N_READY_CHARS): New macro: Returns number of unread
characters in a port. Returns wrong answer if SCM_CRDYP is false.
(struct scm_port_table): New fields: `entry' contains port table
index, `cp' points to last unread char, `cbuf' is the buffer for
unread chars, `cbufend' points after end of the character buffer.
* ports.h, ports.c (scm_unread_string): New procedure.
(scm_grow_port_cbuf): New function.
* ports.c (scm_add_to_port_table, scm_remove_from_port_table):
Handle new fields.
(scm_generic_fgets), fports.c (local_fgets): Use a loop
to read unread characters. Use SCM_TRY_CLRDY instead of
SCM_CLRDY.
* ioext.c (scm_ftell): Use SCM_N_READY_CHARS to correct position.
* genio.c (scm_getc): Use SCM_TRY_CLRDY instead of SCM_CLRDY.
* genio.c, genio.h (scm_ungets): New function.
* genio.c (scm_puts): Removed mysterious TRANSCRIPT_SUPPORT code
sections.
1998-10-28 Mikael Djurfeldt <mdj@mdj.nada.kth.se>
* threads.h (scm_thread_sleep, scm_thread_usleep): Fixed