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dahdi: Use osmo_revbytebits_buf() instead of local flip table 

We've had osmo_revbytebits_buf() in libosmocore for ages.  As it
recently turned out, the flip_bits[] lookup table approach implemented
here is faster at least on x86 systems of the last decade or so.

As of Change-Id I25029fe7e54c92979fb0119992fb8dc167e1536e in
libosmocore, it has been migrated to the lookup table approach. This
means there's no performance penalty of migrating to using it, and
hence no reason whatsoever to have a private implementation here.

Change-Id: I285a87a9fc6abae7d8b47923a46cd082f46829f8
This commit is contained in:
Harald Welte 2020-08-02 10:33:29 +02:00
parent 58538de143
commit 182957bf69
1 changed files with 8 additions and 41 deletions
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49
src/input/dahdi.c
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@ -329,33 +329,6 @@ static int handle_hdlc_read(struct osmo_fd *bfd)
static int invertbits = 1;
static uint8_t flip_table[256];
static void init_flip_bits(void)
{
int i,k;
for (i = 0 ; i < 256 ; i++) {
uint8_t sample = 0 ;
for (k = 0; k<8; k++) {
if ( i & 1 << k ) sample |= 0x80 >> k;
}
flip_table[i] = sample;
}
}
static uint8_t * flip_buf_bits ( uint8_t * buf , int len)
{
int i;
uint8_t * start = buf;
for (i = 0 ; i < len; i++) {
buf[i] = flip_table[(uint8_t)buf[i]];
}
return start;
}
/* write to a B channel TS */
static int handle_tsX_write(struct osmo_fd *bfd)
{
@ -376,9 +349,8 @@ static int handle_tsX_write(struct osmo_fd *bfd)
LOGPITS(e1i_ts, DLMIB, LOGL_DEBUG, "BCHAN TX: %s\n", osmo_hexdump(tx_buf, D_BCHAN_TX_GRAN));
if (invertbits) {
flip_buf_bits(tx_buf, ret);
}
if (invertbits)
osmo_revbytebits_buf(tx_buf, ret);
ret = write(bfd->fd, tx_buf, ret);
if (ret < D_BCHAN_TX_GRAN)
@ -407,9 +379,8 @@ static int handle_tsX_read(struct osmo_fd *bfd)
return ret;
}
if (invertbits) {
flip_buf_bits(msg->data, ret);
}
if (invertbits)
osmo_revbytebits_buf(msg->data, ret);
msgb_put(msg, ret);
@ -447,9 +418,8 @@ static int handle_ts_raw_write(struct osmo_fd *bfd)
LOGPITS(e1i_ts, DLMIB, LOGL_DEBUG, "RAW CHAN TX: %s\n", osmo_hexdump(msg->data, msg->len));
if (0/*invertbits*/) {
flip_buf_bits(msg->data, msg->len);
}
if (0/*invertbits*/)
osmo_revbytebits_buf(msg->data, msg->len);
ret = write(bfd->fd, msg->data, msg->len);
if (ret < msg->len)
@ -476,9 +446,8 @@ static int handle_ts_raw_read(struct osmo_fd *bfd)
return ret;
}
if (0/*invertbits*/) {
flip_buf_bits(msg->data, ret);
}
if (0/*invertbits*/)
osmo_revbytebits_buf(msg->data, ret);
msgb_put(msg, ret);
@ -763,8 +732,6 @@ static int dahdi_e1_line_update(struct e1inp_line *line)
int e1inp_dahdi_init(void)
{
init_flip_bits();
/* register the driver with the core */
return e1inp_driver_register(&dahdi_driver);
}