It seems like I'm always replying to something
that is already out of date. I either type too
slow or I type too much. Or both. :-)
I decided to start looking at the code. I don't
have a dev setup, I'm just looking at gitweb.
I hope I'm accessing the latest, although
for hal_lib I imagine there haven't been many
changes.
The code below is from hal_lib.h, line numbers
hopefully match the current revision.
Note that "net" isn't a core hal_lib command.
The core commands are creating a signal
and linking a single pin to a signal. A net
command is parsed and translated into
multiple core commands. If the signal doesn't
exist it is created, then each pin is individually
linked to it in the order that they appear in
the net command.
This code is from the link command:
Enforcement of linking rules, either of
these can reject the link command:
1077 /* linking output pin to sig that already has output or I/O pins? */
1078 if ((pin->dir == HAL_OUT) && ((sig->writers > 0) || (sig->bidirs > 0
))) {
1085 /* linking bidir pin to sig that already has output pin? */
1086 if ((pin->dir == HAL_IO) && (sig->writers > 0)) {
If the link is allowed, the counts are updated:
1098 /* update the signal's reader/writer/bidir counts */
1099 if ((pin->dir & HAL_IN) != 0) {
1100 sig->readers++;
1101 }
1102 if (pin->dir == HAL_OUT) {
1103 sig->writers++;
1104 }
1105 if (pin->dir == HAL_IO) {
1106 sig->bidirs++;
1107 }
I think that HAL_DRIVING_VALUE more-or-less
duplicates this functionality.
Implementation of the "copy dummy to signal" fix would look
something like:
1093 /* everything is OK, make the new link */
1094 data_ptr_addr = SHMPTR(pin->data_ptr_addr);
1095 comp = SHMPTR(pin->owner_ptr);
1096 data_addr = comp->shmem_base + sig->data_ptr;
1097 *data_ptr_addr = data_addr;
new if (( sig->readers == 0 ) && ( sig->writers == 0 ) && ( sig->bidirs ==
0 )) {
new /* this is the first pin for this signal, copy value from pin's
"dummy" field */
new memcpy(data_addr, &pin->dummysig, sizeof(hal_data_u));
1098 /* update the signal's reader/writer/bidir counts */
--
John Kasunich
[email protected]
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