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sercon: Fix missing GET_LOW() to access rx_bytes 

The variable rx_bytes is marked VARLOW, but there was a missing
GET_LOW() to access rx_bytes.  Fix by copying rx_bytes to a local
variable and avoid the repetitive segment memory accesses.

Reported-by: Gabe Black <gabe.black@gmail.com>
Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
Kevin O'Connor 2022-01-19 19:07:47 -05:00
parent 6d462830e7
commit 15a102e062
1 changed files with 11 additions and 9 deletions
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20
src/sercon.c
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@ -626,7 +626,7 @@ sercon_check_event(void)
u16 addr = GET_LOW(sercon_port);
u16 keycode;
u8 byte, count = 0;
int seq, chr;
int seq;
// check to see if there is a active serial port
if (!addr)
@ -640,20 +640,23 @@ sercon_check_event(void)
// read all available data
while (inb(addr + SEROFF_LSR) & 0x01) {
byte = inb(addr + SEROFF_DATA);
if (GET_LOW(rx_bytes) < sizeof(rx_buf)) {
SET_LOW(rx_buf[rx_bytes], byte);
SET_LOW(rx_bytes, GET_LOW(rx_bytes) + 1);
u8 rb = GET_LOW(rx_bytes);
if (rb < sizeof(rx_buf)) {
SET_LOW(rx_buf[rb], byte);
SET_LOW(rx_bytes, rb + 1);
count++;
}
}
for (;;) {
// no (more) input data
if (!GET_LOW(rx_bytes))
u8 rb = GET_LOW(rx_bytes);
if (!rb)
return;
// lookup escape sequences
if (GET_LOW(rx_bytes) > 1 && GET_LOW(rx_buf[0]) == 0x1b) {
u8 next_char = GET_LOW(rx_buf[0]);
if (rb > 1 && next_char == 0x1b) {
seq = findseq();
if (seq >= 0) {
enqueue_key(GET_GLOBAL(termseq[seq].keycode));
@ -664,12 +667,11 @@ sercon_check_event(void)
// Seems we got a escape sequence we didn't recognise.
// -> If we received data wait for more, maybe it is just incomplete.
if (GET_LOW(rx_buf[0]) == 0x1b && count)
if (next_char == 0x1b && count)
return;
// Handle input as individual char.
chr = GET_LOW(rx_buf[0]);
keycode = ascii_to_keycode(chr);
keycode = ascii_to_keycode(next_char);
if (keycode)
enqueue_key(keycode);
shiftbuf(1);