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telnet: speed up processing of network input

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function                                             old     new   delta
telnet_main                                         1482    1492     +10

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2019-01-06 18:41:11 +01:00
parent 1c952ba206
commit 5bfc4a32fd
1 changed files with 42 additions and 39 deletions
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55
networking/telnet.c
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@ -244,25 +244,34 @@ static void handle_net_output(int len)
static void handle_net_input(int len)
{
byte c;
int i;
int cstart = 0;
for (i = 0; i < len; i++) {
byte c = G.buf[i];
int cstart;
i = 0;
//bb_error_msg("[%u,'%.*s']", G.telstate, len, G.buf);
if (G.telstate == TS_NORMAL) { /* most typical state */
if (c == IAC) {
cstart = i;
G.telstate = TS_IAC;
}
else if (c == '\r') {
cstart = i + 1;
G.telstate = TS_CR;
}
/* No IACs were seen so far, no need to copy
* bytes within G.buf: */
while (i < len) {
c = G.buf[i];
i++;
if (c == IAC) /* unlikely */
goto got_IAC;
if (c != '\r') /* likely */
continue;
G.telstate = TS_CR;
cstart = i;
goto got_special;
}
full_write(STDOUT_FILENO, G.buf, len);
return;
got_IAC:
G.telstate = TS_IAC;
cstart = i - 1;
got_special: ;
}
for (; i < len; i++) {
c = G.buf[i];
switch (G.telstate) {
case TS_CR:
@ -278,20 +287,19 @@ static void handle_net_input(int len)
/* Similar to NORMAL, but in TS_COPY we need to copy bytes */
if (c == IAC)
G.telstate = TS_IAC;
else
else {
G.buf[cstart++] = c;
if (c == '\r')
G.telstate = TS_CR;
}
break;
case TS_IAC: /* Prev char was IAC */
if (c == IAC) { /* IAC IAC -> one IAC */
switch (c) {
case IAC: /* IAC IAC -> one IAC */
G.buf[cstart++] = c;
G.telstate = TS_COPY;
break;
}
/* else */
switch (c) {
case SB:
G.telstate = TS_SUB1;
break;
@ -320,17 +328,12 @@ static void handle_net_input(int len)
}
}
if (G.telstate != TS_NORMAL) {
/* We had some IACs, or CR */
if (G.iaclen)
iac_flush();
if (G.telstate == TS_COPY) /* we aren't in the middle of IAC */
G.telstate = TS_NORMAL;
len = cstart;
}
if (len)
full_write(STDOUT_FILENO, G.buf, len);
if (cstart != 0)
full_write(STDOUT_FILENO, G.buf, cstart);
}
static void put_iac(int c)