femtolisp/llt/scrap

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2008-06-30 21:53:51 -04:00
/* null stream */
off_t null_seek(struct _stream *s, off_t where)
{
return -1;
}
off_t null_skip(struct _stream *s, off_t offs)
{
return 0;
}
off_t null_seek_end(struct _stream *s)
{
return -1;
}
size_t null_read(struct _stream *s, char *dest, size_t size)
{
return 0;
}
size_t null_write(struct _stream *s, char *data, size_t size)
{
return 0;
}
size_t null_trunc(struct _stream *s, size_t size)
{
return 0;
}
void null_flush(struct _stream *s)
{
}
bool_t null_eof(struct _stream *s)
{
return true;
}
void free_null_stream(stream_t *s)
{
}
DLLEXPORT stream_interface_t null_funcs =
{free_null_stream, null_seek, null_seek_end, null_skip,
null_read, null_write, null_trunc, null_eof, null_flush};
stream_t *nullstream_new()
{
stream_t *s;
s = (stream_t*)obj_alloc(stream_pool);
s->funcs = &null_funcs;
s->byteswap = false;
s->bitpos = s->bitbuf = 0;
s->pos = 0;
return s;
}
void free_roms_stream(stream_t *s)
{
(void)s;
}
size_t roms_write(struct _stream *s, char *data, size_t size)
{
(void)s;
(void)data;
(void)size;
return 0;
}
size_t roms_trunc(struct _stream *s, size_t size)
{
(void)size;
return s->size;
}
void roms_flush(struct _stream *s)
{
s->bitpos = 0;
}
stream_interface_t roms_funcs =
{free_roms_stream, ms_seek, ms_seek_end, ms_skip,
ms_read, roms_write, roms_trunc, ms_eof, roms_flush};
/* read-only memory stream */
stream_t *romemstream_new(stream_t *s, char *data, size_t len)
{
memstream_new(s, 0);
s->funcs = &roms_funcs;
s->data = data;
s->size = len;
s->maxsize = len+1;
s->pos = 0;
s->bitpos = s->bitbuf = 0;
s->byteswap = false;
return s;
}
int stream_vput_int(stream_t *s, int nargs, ...)
{
u_int32_t val, i, c=0;
va_list ap;
va_start(ap, nargs);
for(i=0; i < (unsigned)nargs; i++) {
val = va_arg(ap, int);
c += stream_put_int(s, val);
}
va_end(ap);
return c;
}
// after this function you are guaranteed to be able to perform
// operations of the kind requested.
static int _ios_setstate(ios_t *s, iostate_t newstate)
{
if (s->state != newstate) {
if (s->state == iost_none || s->bm == bm_mem || s->bm == bm_none) {
}
else if (s->state == iost_rd) {
// reading -> writing; try to put back unused buffer data
// todo: another possibility here is to seek back s->size bytes,
// not move any data, and retain the ability to seek backwards
// within the buffer. the downside to that would be redundant
// writes of stuff that was already in the file.
ios_skip(s, -(off_t)(s->size - s->bpos));
// todo: if the seek fails...?
_discard_partial_buffer(s);
// note: bitpos is left alone, so if all goes well we pick up
// writing exactly where we stopped reading.
}
else if (s->state == iost_wr) {
ios_flush(s);
}
s->state = newstate;
}
// now make sure buffer is set up for the state we're in
if (s->state == iost_wr) {
// TODO: fill buffer if stenciling is requested
}
else if (s->state == iost_rd) {
// TODO: fill buffer if needed
}
return 0;
}
/* convert double to int64 in software */
int64_t double_to_int64(double d)
{
int64_t i;
int ex;
union ieee754_double dl;
if (fabs(d) < 1) return 0;
dl.d = d;
ex = dl.ieee.exponent - IEEE754_DOUBLE_BIAS;
// fill mantissa into bits 0 to 51
i = ((((int64_t)dl.mantissa0)<<32) | ((int64_t)dl.mantissa1));
if (ex < 52)
i >>= (52-ex);
else if (ex > 52)
i <<= (ex-52);
}