--skip: use seconds instead of raw samples

1 files changed, 12 insertions, 10 deletions

diff --git a/bin/msp430-etv b/bin/msp430-etv
index 424a077..51c9013 100755
--- a/bin/msp430-etv
+++ b/bin/msp430-etv
@@ -252,10 +252,10 @@ def main():
     )
     parser.add_argument(
         "--skip",
-        metavar="COUNT",
+        metavar="N",
         type=int,
         default=0,
-        help="Skip COUNT data samples. This is useful to avoid startup code influencing the results of a long-running measurement",
+        help="Skip the first N seconds of data. This is useful to avoid startup code influencing the results of a long-running measurement",
     )
     parser.add_argument(
         "--limit",
@@ -324,14 +324,13 @@ def main():
     data_count = sum(map(lambda x: len(x) > 0 and x[0] != "#", lines))
     data_lines = filter(lambda x: len(x) > 0 and x[0] != "#", lines)
 
-    data = np.empty((data_count - args.skip, 4))
+    data = np.empty((data_count, 4))
+    skip_offset = 0
+    limit_index = data_count
 
     energy_overflow_count = 0
     prev_total_energy = 0
     for i, line in enumerate(data_lines):
-        if i < args.skip:
-            continue
-
         fields = line.split(" ")
         if len(fields) == 4:
             timestamp, current, voltage, total_energy = map(int, fields)
@@ -345,14 +344,17 @@ def main():
         prev_total_energy = total_energy
         total_energy += energy_overflow_count * (2 ** 32)
 
+        if args.skip is not None and timestamp * 1e-6 < args.skip:
+            skip_offset = i + 1
+            continue
+
         if args.limit is not None and timestamp * 1e-6 > args.limit:
-            final_index = i - args.skip - 1
+            limit_index = i - 1
             break
 
-        data[i - args.skip] = [timestamp, current, voltage, total_energy]
+        data[i] = [timestamp, current, voltage, total_energy]
 
-    if args.limit is not None:
-        data = data[:final_index]
+    data = data[skip_offset:limit_index]
 
     m_duration_us = data[-1, 0] - data[0, 0]
     m_energy_nj = data[-1, 3] - data[0, 3]