FastWaveBackend/src/vcd/signal.rs
2022-09-08 09:59:24 -04:00

460 lines
17 KiB
Rust

use super::{ScopeIdx, SignalIdx};
use num::{BigUint, Zero};
// Index to the least significant byte of a timestamp
// value on the timeline
#[derive(Debug, Copy, Clone)]
pub struct LsbIdxOfTmstmpValOnTmln(pub(super) u32);
#[derive(Debug)]
pub enum SigType {
Integer,
Parameter,
Real,
Reg,
Str,
Wire,
Tri1,
Time,
}
#[derive(Debug)]
pub(super) enum TimelineQueryResults {
BigUint(BigUint),
String(String),
}
#[derive(Debug)]
pub enum Signal {
Data {
name: String,
sig_type: SigType,
// I've seen a 0 bit signal parameter in a xilinx
// simulation before that gets assigned 1 bit values.
// I consider this to be bad behavior. We capture such
// errors in the following type:
signal_error: Option<String>,
num_bits: Option<u16>,
num_bytes: Option<u8>,
// TODO : may be able to remove self_idx
self_idx: SignalIdx,
// A signal may take on a new value and hold that value
// for sometime. We only need to record the value of a signal
// when it changes(the is what VCDs tend to do).
// A signal may need x amount of bytes to record its largest possible
// value, so we record every single value of a given signal as a sequence
// of x number of u8s.
// For example, we might find that `my_signal.nums_encoded_as_fixed_width_le_u8`
// has two 32 bit values, namely, 1 and 2, encoded as follows:
// my_signal.nums_encoded_as_fixed_width_le_u8 = vec![1u8, 0u8, 0u8, 0u8, 2u8, 0u8, 0u8, 0u8];
nums_encoded_as_fixed_width_le_u8: Vec<u8>,
string_vals: Vec<String>,
// we could do Vec<(LsbIdxOfTmstmpValOnTmln, u8)>, but I suspect that
// Vec<LsbIdxOfTmstmpValOnTmln> is more cache friendly.
// We use ``LsbIdxOfTmstmpValOnTmln`` to index into the LSB of a particular
// timestamp encoded as the minimu length u8 sequence within
// ``vcd.tmstmps_encoded_as_u8s``, and we use the values in
// ``byte_len_of_num_tmstmp_vals_on_tmln`` to determine how many u8 values
// a particular timestamp is composed of.
lsb_indxs_of_num_tmstmp_vals_on_tmln: Vec<LsbIdxOfTmstmpValOnTmln>,
byte_len_of_num_tmstmp_vals_on_tmln: Vec<u8>,
byte_len_of_string_tmstmp_vals_on_tmln: Vec<u8>,
lsb_indxs_of_string_tmstmp_vals_on_tmln: Vec<LsbIdxOfTmstmpValOnTmln>,
scope_parent: ScopeIdx,
},
Alias {
name: String,
signal_alias: SignalIdx,
},
}
#[derive(Debug)]
pub enum SignalErrors {
PreTimeline {
desired_time: BigUint,
timeline_start_time: BigUint,
},
EmptyTimeline,
TimelineNotMultiple,
StrTmlnLenMismatch,
OrderingFailure {
lhs_time: BigUint,
mid_time: BigUint,
rhs_time: BigUint,
},
PointsToAlias,
NoNumBytes,
Other(String),
}
// these are thin type aliases primarily to make code more readable later on
type TimeStamp = BigUint;
type SignalValNum = BigUint;
// getter functions
impl Signal {
pub fn self_idx(&self) -> Result<SignalIdx, String> {
match self {
Signal::Data { self_idx, ..} => {return Ok(self_idx.clone())},
Signal::Alias { .. } => Err(format!(
"Error near {}:{}. A signal alias shouldn't \
point to a signal alias.",
file!(),
line!()
)),
}
}
pub fn name(&self) -> String {
match self {
Signal::Data { name, ..} => name,
Signal::Alias { name, .. } => name
}.clone()
}
}
impl Signal {
pub(super) fn bytes_required(num_bits: u16, name: &String) -> Result<u8, String> {
let bytes_required = (num_bits / 8) + if (num_bits % 8) > 0 { 1 } else { 0 };
let bytes_required = u8::try_from(bytes_required).map_err(|_| {
format!(
"Error near {}:{}. Signal {name} of length num_bits requires \
{bytes_required} > 256 bytes.",
file!(),
line!()
)
})?;
Ok(bytes_required)
}
pub(super) fn time_and_str_val_at_event_idx(
&self,
event_idx: usize,
tmstmps_encoded_as_u8s: &Vec<u8>,
) -> Result<(TimeStamp, &str), SignalErrors> {
let (
string_vals,
lsb_indxs_of_string_tmstmp_vals_on_tmln,
byte_len_of_string_tmstmp_vals_on_tmln,
) = match self {
Signal::Data {
string_vals,
lsb_indxs_of_string_tmstmp_vals_on_tmln,
byte_len_of_string_tmstmp_vals_on_tmln,
..
} => Ok((
string_vals,
lsb_indxs_of_string_tmstmp_vals_on_tmln,
byte_len_of_string_tmstmp_vals_on_tmln,
)),
Signal::Alias { .. } => Err(SignalErrors::PointsToAlias),
}?;
// get index
let LsbIdxOfTmstmpValOnTmln(timestamp_idx) =
lsb_indxs_of_string_tmstmp_vals_on_tmln[event_idx];
let timestamp_idx = timestamp_idx as usize;
// form timestamp
let byte_len = byte_len_of_string_tmstmp_vals_on_tmln[event_idx] as usize;
let timestamp = &tmstmps_encoded_as_u8s[timestamp_idx..(timestamp_idx + byte_len)];
let timestamp = BigUint::from_bytes_le(timestamp);
// get signal value
let signal_val = string_vals[event_idx].as_str();
Ok((timestamp, signal_val))
}
pub(super) fn time_and_num_val_at_event_idx(
&self,
event_idx: usize,
tmstmps_encoded_as_u8s: &Vec<u8>,
) -> Result<(TimeStamp, SignalValNum), SignalErrors> {
let (
num_bytes,
nums_encoded_as_fixed_width_le_u8,
lsb_indxs_of_num_tmstmp_vals_on_tmln,
byte_len_of_num_tmstmp_vals_on_tmln,
) = match self {
Signal::Data {
num_bytes,
nums_encoded_as_fixed_width_le_u8,
lsb_indxs_of_num_tmstmp_vals_on_tmln,
byte_len_of_num_tmstmp_vals_on_tmln,
..
} => Ok((
num_bytes,
nums_encoded_as_fixed_width_le_u8,
lsb_indxs_of_num_tmstmp_vals_on_tmln,
byte_len_of_num_tmstmp_vals_on_tmln,
)),
Signal::Alias { .. } => Err(SignalErrors::PointsToAlias),
}?;
// get index
let LsbIdxOfTmstmpValOnTmln(timestamp_idx) =
lsb_indxs_of_num_tmstmp_vals_on_tmln[event_idx];
let timestamp_idx = timestamp_idx as usize;
// form timestamp
let byte_len = byte_len_of_num_tmstmp_vals_on_tmln[event_idx] as usize;
let timestamp = &tmstmps_encoded_as_u8s[timestamp_idx..(timestamp_idx + byte_len)];
let timestamp = BigUint::from_bytes_le(timestamp);
// get signal value
let bytes_per_value = num_bytes.ok_or_else(|| SignalErrors::NoNumBytes)?;
let bytes_per_value = bytes_per_value as usize;
let start_idx = event_idx * bytes_per_value;
let end_idx = (event_idx + 1) * bytes_per_value;
let signal_val = &nums_encoded_as_fixed_width_le_u8[start_idx..end_idx];
let signal_val = BigUint::from_bytes_le(signal_val);
Ok((timestamp, signal_val))
}
pub fn query_string_val_on_tmln(
&self,
desired_time: &BigUint,
tmstmps_encoded_as_u8s: &Vec<u8>,
all_signals: &Vec<Signal>,
) -> Result<String, SignalErrors> {
let signal_idx = match self {
Self::Data { self_idx, .. } => {
let SignalIdx(idx) = self_idx;
*idx
}
Self::Alias {
name: _,
signal_alias,
} => {
let SignalIdx(idx) = signal_alias;
*idx
}
};
// if the signal idx points to data variant of the signal,
// extract:
// 1. the vector of string values
// 2. the vector of indices into timeline where events occur
// for this signal
// else we propagate Err(..).
let (string_vals, lsb_indxs_of_string_tmstmp_vals_on_tmln) =
match &all_signals[signal_idx] {
Signal::Data {
ref string_vals,
ref lsb_indxs_of_string_tmstmp_vals_on_tmln,
..
} => {
Ok((
string_vals,
lsb_indxs_of_string_tmstmp_vals_on_tmln,
))
}
Signal::Alias { .. } => Err(SignalErrors::PointsToAlias),
}?;
// this signal should at least have some events, otherwise, trying to index into
// an empty vector later on would fail
if lsb_indxs_of_string_tmstmp_vals_on_tmln.is_empty() {
return Err(SignalErrors::EmptyTimeline);
}
// the vector of string timeline lsb indices should have the same
// length as the vector of string values
if string_vals.len() != lsb_indxs_of_string_tmstmp_vals_on_tmln.len() {
return Err(SignalErrors::StrTmlnLenMismatch);
}
// check if we're requesting a value that occurs before the recorded
// start of the timeline
let (timeline_start_time, _) =
self.time_and_str_val_at_event_idx(0, tmstmps_encoded_as_u8s)?;
if *desired_time < timeline_start_time {
return Err(SignalErrors::PreTimeline {
desired_time: desired_time.clone(),
timeline_start_time: timeline_start_time,
});
}
let mut lower_idx = 0usize;
let mut upper_idx = lsb_indxs_of_string_tmstmp_vals_on_tmln.len() - 1;
let (timeline_end_time, timeline_end_val) =
self.time_and_str_val_at_event_idx(upper_idx, tmstmps_encoded_as_u8s)?;
// check if we're requesting a value that occurs beyond the end of the timeline,
// if so, return the last value in this timeline
if *desired_time > timeline_end_time {
return Ok(timeline_end_val.to_string());
}
// This while loop is the meat of the lookup. Performance is log2(n),
// where n is the number of events on the timeline.
// We can assume that by the time we get here, that the desired_time
// is an event that occurs on the timeline, given that we handle any events
// occuring after or before the recorded tiimeline in the code above.
while lower_idx <= upper_idx {
let mid_idx = lower_idx + ((upper_idx - lower_idx) / 2);
let (curr_time, curr_val) =
self.time_and_str_val_at_event_idx(mid_idx, tmstmps_encoded_as_u8s)?;
let ordering = curr_time.cmp(desired_time);
match ordering {
std::cmp::Ordering::Less => {
lower_idx = mid_idx + 1;
}
std::cmp::Ordering::Equal => {
return Ok(curr_val.to_string());
}
std::cmp::Ordering::Greater => {
upper_idx = mid_idx - 1;
}
}
}
let (left_time, left_val) =
self.time_and_str_val_at_event_idx(lower_idx - 1, tmstmps_encoded_as_u8s)?;
let (right_time, _) =
self.time_and_str_val_at_event_idx(lower_idx, tmstmps_encoded_as_u8s)?;
let ordered_left = left_time < *desired_time;
let ordered_right = *desired_time < right_time;
if !(ordered_left && ordered_right) {
return Err(SignalErrors::OrderingFailure {
lhs_time: left_time,
mid_time: desired_time.clone(),
rhs_time: right_time,
});
}
return Ok(left_val.to_string());
}
pub fn query_num_val_on_tmln(
&self,
desired_time: &BigUint,
tmstmps_encoded_as_u8s: &Vec<u8>,
all_signals: &Vec<Signal>,
) -> Result<BigUint, SignalErrors> {
let signal_idx = match self {
Self::Data { self_idx, .. } => {
let SignalIdx(idx) = self_idx;
*idx
}
Self::Alias {
name: _,
signal_alias,
} => {
let SignalIdx(idx) = signal_alias;
*idx
}
};
// if the signal idx points to data variant of the signal,
// extract:
// 1. the vector of LE u8 compressed values
// 2. the vector of indices into timeline where events occur
// for this signal
// 3. the number of bytes per value for this signal
// else we propagate Err(..).
let (nums_encoded_as_fixed_width_le_u8, lsb_indxs_of_num_tmstmp_vals_on_tmln, num_bytes) =
match &all_signals[signal_idx] {
Signal::Data {
num_bytes,
ref nums_encoded_as_fixed_width_le_u8,
ref lsb_indxs_of_num_tmstmp_vals_on_tmln,
..
} => {
if num_bytes.is_none() {
return Err(SignalErrors::NoNumBytes);
}
Ok((
nums_encoded_as_fixed_width_le_u8,
lsb_indxs_of_num_tmstmp_vals_on_tmln,
num_bytes,
))
}
Signal::Alias { .. } => Err(SignalErrors::PointsToAlias),
}?;
// this signal should at least have some events, otherwise, trying to index into
// an empty vector later on would fail
if lsb_indxs_of_num_tmstmp_vals_on_tmln.is_empty() {
return Err(SignalErrors::EmptyTimeline);
}
// assertion that value_sequence is a proper multiple of
// timeline_markers
let bytes_required = num_bytes.ok_or_else(|| {
SignalErrors::Other(format!(
"Error near {}:{}. num_bytes empty.",
file!(),
line!()
))
})?;
if nums_encoded_as_fixed_width_le_u8.len()
!= (lsb_indxs_of_num_tmstmp_vals_on_tmln.len() * (bytes_required as usize))
{
return Err(SignalErrors::TimelineNotMultiple);
}
// check if we're requesting a value that occurs before the recorded
// start of the timeline
let (timeline_start_time, _) =
self.time_and_num_val_at_event_idx(0, tmstmps_encoded_as_u8s)?;
if *desired_time < timeline_start_time {
return Err(SignalErrors::PreTimeline {
desired_time: desired_time.clone(),
timeline_start_time: timeline_start_time,
});
}
let mut lower_idx = 0usize;
let mut upper_idx = lsb_indxs_of_num_tmstmp_vals_on_tmln.len() - 1;
let (timeline_end_time, timeline_end_val) =
self.time_and_num_val_at_event_idx(upper_idx, tmstmps_encoded_as_u8s)?;
// check if we're requesting a value that occurs beyond the end of the timeline,
// if so, return the last value in this timeline
if *desired_time > timeline_end_time {
return Ok(timeline_end_val);
}
// This while loop is the meat of the lookup. Performance is log2(n),
// where n is the number of events on the timeline.
// We can assume that by the time we get here, that the desired_time
// is an event that occurs on the timeline, given that we handle any events
// occuring after or before the recorded tiimeline in the code above.
while lower_idx <= upper_idx {
let mid_idx = lower_idx + ((upper_idx - lower_idx) / 2);
let (curr_time, curr_val) =
self.time_and_num_val_at_event_idx(mid_idx, tmstmps_encoded_as_u8s)?;
let ordering = curr_time.cmp(desired_time);
match ordering {
std::cmp::Ordering::Less => {
lower_idx = mid_idx + 1;
}
std::cmp::Ordering::Equal => {
return Ok(curr_val);
}
std::cmp::Ordering::Greater => {
upper_idx = mid_idx - 1;
}
}
}
let (left_time, left_val) =
self.time_and_num_val_at_event_idx(lower_idx - 1, tmstmps_encoded_as_u8s)?;
let (right_time, _) =
self.time_and_num_val_at_event_idx(lower_idx, tmstmps_encoded_as_u8s)?;
let ordered_left = left_time < *desired_time;
let ordered_right = *desired_time < right_time;
if !(ordered_left && ordered_right) {
return Err(SignalErrors::OrderingFailure {
lhs_time: left_time,
mid_time: desired_time.clone(),
rhs_time: right_time,
});
}
return Ok(left_val);
}
}