src/lib.rs

@@ -7,6 +7,6 @@ mod vcd;
 pub use vcd::parse::parse_vcd;
 pub use vcd::types::{ScopeIdx, SignalIdx, VCD};
 pub use vcd::types::{Metadata, Timescale, Version};
-pub use vcd::signal::{Signal};
+pub use vcd::signal::{Signal, SignalValue};
 
 pub use num::BigUint;

src/vcd/parse.rs

@@ -27,6 +27,7 @@ pub fn parse_vcd(file: File) -> Result<super::types::VCD, String> {
         all_signals: vec![],
         all_scopes: vec![],
         root_scopes: vec![],
+        largest_timestamp: None
     };
 
     scopes::parse_scopes(&mut word_gen, &mut vcd, &mut signal_map)?;

src/vcd/parse/events.rs

@@ -40,14 +40,14 @@ pub(super) fn parse_events<'a>(
             "#" => {
                 let value = &word[1..];
                 let (f, l) = (file!(), line!());
-                let value = BigUint::parse_bytes(value.as_bytes(), 10)
+                let value_biguint = BigUint::parse_bytes(value.as_bytes(), 10)
                     .ok_or(())
                     .map_err(|_| {
                         format!(
                             "Error near {f}:{l}. Failed to parse {value} as BigInt at {cursor:?}"
                         )
                     })?;
-                let mut value = value.to_bytes_le();
+                let mut value = value_biguint.to_bytes_le();
                 // TODO : u32 helps with less memory, but should ideally likely be
                 // configurable.
                 curr_tmstmp_len_u8 = u8::try_from(value.len()).map_err(|_| {
@@ -66,6 +66,7 @@ pub(super) fn parse_events<'a>(
                         )
                     })?;
                 vcd.tmstmps_encoded_as_u8s.append(&mut value);
+                vcd.largest_timestamp = Some(value_biguint);
             }
 
             // handle the case of an n bit signal whose value must be parsed
@@ -134,6 +135,7 @@ pub(super) fn parse_events<'a>(
                         lsb_indxs_of_num_tmstmp_vals_on_tmln,
                         byte_len_of_num_tmstmp_vals_on_tmln,
                         lsb_indxs_of_string_tmstmp_vals_on_tmln,
+                        byte_len_of_string_tmstmp_vals_on_tmln,
                         ..
                     } => {
                         // we've already identified in a prior loop iteration that the signal has
@@ -176,6 +178,7 @@ pub(super) fn parse_events<'a>(
                         if store_as_string {
                             lsb_indxs_of_string_tmstmp_vals_on_tmln
                                 .push(LsbIdxOfTmstmpValOnTmln(curr_tmstmp_lsb_idx));
+                            byte_len_of_string_tmstmp_vals_on_tmln.push(curr_tmstmp_len_u8);
                             string_vals.push(value_string);
                             Ok(())
                         } else {

src/vcd/signal.rs

@@ -23,8 +23,8 @@ pub enum SigType {
     Time,
 }
 
-#[derive(Debug)]
-pub(super) enum TimelineQueryResults {
+#[derive(Debug, PartialEq)]
+pub enum SignalValue {
     BigUint(BigUint),
     String(String),
 }
@@ -36,13 +36,19 @@ impl<'a> Signal<'a> {
         let Signal(signal_enum) = &self;
         signal_enum.name()
     }
+
+    pub fn num_bits(&self) -> Option<u16> {
+        let Signal(signal_enum) = &self;
+        signal_enum.bits_required()
+    }
+
     pub fn query_string_val_on_tmln(
         &self,
         desired_time: &BigUint,
         vcd: &types::VCD,
     ) -> Result<String, SignalErrors> {
         let Signal(signal_enum) = &self;
-        signal_enum.query_string_val_on_tmln(desired_time, &vcd.tmstmps_encoded_as_u8s, &vcd.all_signals)
+        signal_enum.query_string_val_on_tmln(desired_time, &vcd.tmstmps_encoded_as_u8s, &vcd.all_signals).map(|(val, _)| val)
     }
     pub fn query_num_val_on_tmln(
         &self,
@@ -50,7 +56,44 @@ impl<'a> Signal<'a> {
         vcd: &types::VCD,
     ) -> Result<BigUint, SignalErrors> {
         let Signal(signal_enum) = &self;
-        signal_enum.query_num_val_on_tmln(desired_time, &vcd.tmstmps_encoded_as_u8s, &vcd.all_signals)
+        signal_enum.query_num_val_on_tmln(desired_time, &vcd.tmstmps_encoded_as_u8s, &vcd.all_signals).map(|(val, _)| val)
+    }
+
+    pub fn query_val_on_tmln(
+        &self,
+        desired_time: &BigUint,
+        vcd: &types::VCD,
+    ) -> Result<SignalValue, SignalErrors> {
+        let Signal(signal_enum) = &self;
+        let num_val = signal_enum
+            .query_num_val_on_tmln(
+                desired_time,
+                &vcd.tmstmps_encoded_as_u8s,
+                &vcd.all_signals
+            );
+        let str_val = signal_enum
+            .query_string_val_on_tmln(
+                desired_time,
+                &vcd.tmstmps_encoded_as_u8s,
+                &vcd.all_signals
+            );
+
+        // Both num and str will return the newest value that is closest to
+        // the desired time. If both have valid values, select the most recent
+        // one
+        match (num_val, str_val) {
+            (Ok((num_val, num_time)), Ok((str_val, str_time))) => {
+                if num_time > str_time {
+                    Ok(SignalValue::BigUint(num_val))
+                }
+                else {
+                    Ok(SignalValue::String(str_val))
+                }
+            }
+            (Ok((num_val, _)), Err(_)) => Ok(SignalValue::BigUint(num_val)),
+            (Err(_), Ok((str_val, _))) => Ok(SignalValue::String(str_val)),
+            (Err(e), _e) => Err(e)
+        }
     }
 }
 
@@ -187,6 +230,10 @@ impl SignalEnum {
             lsb_indxs_of_string_tmstmp_vals_on_tmln[event_idx];
         let timestamp_idx = timestamp_idx as usize;
 
+        if byte_len_of_string_tmstmp_vals_on_tmln.is_empty() {
+            return Err(SignalErrors::EmptyTimeline);
+        }
+
         // 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)];
@@ -253,6 +300,14 @@ impl SignalEnum {
 
         Ok((timestamp, signal_val))
     }
+
+    fn bits_required(&self) -> Option<u16> {
+        match self {
+            SignalEnum::Data {num_bits, ..} => num_bits.clone(),
+            // TODO: Follow aliases?
+            SignalEnum::Alias { name, signal_alias } => None,
+        }
+    }
 }
 
 // Val and string query functions.
@@ -265,7 +320,7 @@ impl SignalEnum {
         desired_time: &BigUint,
         tmstmps_encoded_as_u8s: &Vec<u8>,
         all_signals: &Vec<SignalEnum>,
-    ) -> Result<String, SignalErrors> {
+    ) -> Result<(String, TimeStamp), SignalErrors> {
         let signal_idx = match self {
             Self::Data { self_idx, .. } => {
                 let SignalIdx(idx) = self_idx;
@@ -319,7 +374,7 @@ impl SignalEnum {
         if *desired_time < timeline_start_time {
             return Err(SignalErrors::PreTimeline {
                 desired_time: desired_time.clone(),
-                timeline_start_time: timeline_start_time,
+                timeline_start_time,
             });
         }
 
@@ -331,7 +386,7 @@ impl SignalEnum {
         // 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());
+            return Ok((timeline_end_val.to_string(), timeline_end_time));
         }
 
         // This while loop is the meat of the lookup. Performance is log2(n),
@@ -350,7 +405,7 @@ impl SignalEnum {
                     lower_idx = mid_idx + 1;
                 }
                 std::cmp::Ordering::Equal => {
-                    return Ok(curr_val.to_string());
+                    return Ok((curr_val.to_string(), curr_time));
                 }
                 std::cmp::Ordering::Greater => {
                     upper_idx = mid_idx - 1;
@@ -373,14 +428,14 @@ impl SignalEnum {
             });
         }
 
-        return Ok(left_val.to_string());
+        Ok((left_val.to_string(), left_time))
     }
     pub fn query_num_val_on_tmln(
         &self,
         desired_time: &BigUint,
         tmstmps_encoded_as_u8s: &Vec<u8>,
         all_signals: &Vec<SignalEnum>,
-    ) -> Result<BigUint, SignalErrors> {
+    ) -> Result<(BigUint, TimeStamp), SignalErrors> {
         let signal_idx = match self {
             Self::Data { self_idx, .. } => {
                 let SignalIdx(idx) = self_idx;
@@ -449,7 +504,7 @@ impl SignalEnum {
         if *desired_time < timeline_start_time {
             return Err(SignalErrors::PreTimeline {
                 desired_time: desired_time.clone(),
-                timeline_start_time: timeline_start_time,
+                timeline_start_time,
             });
         }
 
@@ -461,7 +516,7 @@ impl SignalEnum {
         // 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);
+            return Ok((timeline_end_val, timeline_end_time));
         }
 
         // This while loop is the meat of the lookup. Performance is log2(n),
@@ -480,7 +535,7 @@ impl SignalEnum {
                     lower_idx = mid_idx + 1;
                 }
                 std::cmp::Ordering::Equal => {
-                    return Ok(curr_val);
+                    return Ok((curr_val, curr_time));
                 }
                 std::cmp::Ordering::Greater => {
                     upper_idx = mid_idx - 1;
@@ -503,6 +558,6 @@ impl SignalEnum {
             });
         }
 
-        return Ok(left_val);
+        Ok((left_val, left_time))
     }
 }

src/vcd/types.rs

@@ -5,6 +5,7 @@
 // and the YEHOWSHUA license, both of which can be found at
 // the root of the folder containing the sources for this program.
 use chrono::prelude::{DateTime, Utc};
+use num::BigUint;
 use super::signal::{Signal, SignalEnum};
 
 #[derive(Debug)]
@@ -63,6 +64,7 @@ pub struct VCD {
     pub(super) all_signals: Vec<SignalEnum>,
     pub(super) all_scopes: Vec<Scope>,
     pub(super) root_scopes: Vec<ScopeIdx>,
+    pub(super) largest_timestamp: Option<BigUint>
 }
 
 impl VCD {
@@ -121,4 +123,8 @@ impl VCD {
             )),
         }
     }
+
+    pub fn max_timestamp(&self) -> &Option<BigUint> {
+        &self.largest_timestamp
+    }
 }