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Update and clarify the comments at the top of udevices.c, which should make it easier when someone in the future has to make changes.

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Brian Taylor 2025-09-28 11:59:17 -07:00 committed by Holger Vogt
parent 71614dba3a
commit a99ff45eaf
1 changed files with 45 additions and 18 deletions
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63
src/frontend/udevices.c
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@ -4,10 +4,16 @@
Notes: To translate Pspice U* devices in a subcircuit containing Notes: To translate Pspice U* devices in a subcircuit containing
U* instance and Pspice .model cards, two passes through the subcircuit U* instance and Pspice .model cards, two passes through the subcircuit
are necessary. The first pass is to translate the timing models from are necessary. The first pass is to translate the timing models from
the .model cards. This timing delay information is stored. The second the .model cards. This timing delay information is stored. Also, during
pass is for translating the U* instance cards to generate equivalent the first pass each U* instance in the subcircuit is checked to see
Xspice digital device instances and their timing delay .model cards if it can be translated.
using the previously stored delays.
The second pass is for translating the U* instance cards to generate
equivalent Xspice digital device instances and their timing delay
.model cards using the previously stored delays.
The two pass algorithm is implemented by the function u_instances()
in frontend/inpcompat.c.
Some limitations are: Some limitations are:
No support for CONSTRAINT, RAM, ROM, STIM, PLAs. No support for CONSTRAINT, RAM, ROM, STIM, PLAs.
@ -21,24 +27,45 @@
f_logicexp and f_pindly. f_logicexp and f_pindly.
First pass through a subcircuit. Call initialize_udevice() and read the First pass through a subcircuit. Call initialize_udevice() and read the
.model cards by calling u_process_model_line() (or similar) for each card, .model cards by calling u_process_model_line() for each model card.
The delays for the different types (ugate, utgate, ueff, ugff, udly) are stored The delays for the different types (ugate, utgate, ueff, ugff, udly)
by get_delays_...() and add_delays_to_model_xlator(). Also, during the are stored by:
first pass, check that each U* instance can be translated to Xspice. get_delays_ugate(), get_delays_utgate(), get_delays_ueff(),
get_delays_ugff(), get_delays_udly().
Also, during the first pass, verify that each U* instance can be translated
to Xspice by calling u_check_instance().
If there are any .model or U* instance cards that cannot be processed If there are any .model or U* instance cards that cannot be processed
in the .subckt, then there is no second pass and the .subckt is skipped. in the .subckt, then there is no second pass and the .subckt is skipped.
Second pass through a subcircuit. To translate each U* instance call Second pass through a subcircuit. To translate each U* instance call
u_process_instance_line() (or similar). This calls translate_...() u_process_instance(). This calls:
functions for gates, tristate, flip-flops and latches. translate_...() translate_gate(), translate_ff_latch(), translate_pull(),
calls add_..._inout_timing_model() to parse the U* card, and then calls translate_dlyline()
gen_..._instance(). Creating new cards to replace the U* and .model functions for gates, tristate, flip-flops, latches etc.
cards is done by calling replacement_udevice_cards(), which returns a
list of new cards. The list of cards is then to be inserted after the The translate functions call the corresponding:
.subckt card and before the .ends card. This occurs in the driver add_gate_inout_timing_model(), add_array_inout_timing_model(),
function u_instances() in frontend/inpcom.c. add_compound_inout_timing_model(), add_dff_inout_timing_model(),
Finally, call cleanup_udevice() before repeating the sequence for add_dltch_inout_timing_model(), add_jkff_inout_timing_model(),
another subcircuit. add_srff_inout_timing_model()
when parsing the U* card to add inputs, outputs, and timing model
to an Xspice instance.
Finally, the translate functions call:
gen_gate_instance(), gen_compound_instance(), gen_dff_instance(),
gen_jkff_instance(), gen_dltch_instance(), gen_srff_instance().
Each gen_..._instance() creates new cards to replace the U* and .model
cards.
If all the U* instances and timing models in the subcircuit can be
translated, the driver function u_instances() (in inpcompat.c) will call
replacement_udevice_cards(),
which returns a list of new cards. The list of cards is then inserted
after the .subckt card and before the .ends card.
Finally, the driver calls cleanup_udevice() before repeating the sequence
for another subcircuit.
More explanations are provided below in comments with NOTE. More explanations are provided below in comments with NOTE.
*/ */