auto import from //depot/cupcake/@135843
diff --git a/emulator/qtools/hist_trace.cpp b/emulator/qtools/hist_trace.cpp
new file mode 100644
index 0000000..d2c6a90
--- /dev/null
+++ b/emulator/qtools/hist_trace.cpp
@@ -0,0 +1,64 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <inttypes.h>
+#include "trace_reader.h"
+
+static const int kMaxHistEntries = 256;
+static const int kMaxHistEntries2 = kMaxHistEntries / 2;
+int hist[kMaxHistEntries];
+int underflow, overflow;
+
+int main(int argc, char **argv) {
+ if (argc != 2) {
+ fprintf(stderr, "Usage: %s trace_file\n", argv[0]);
+ exit(1);
+ }
+
+ char *trace_filename = argv[1];
+ TraceReaderBase *trace = new TraceReaderBase;
+ trace->Open(trace_filename);
+
+ uint64_t prev_bb_num = 0;
+ uint64_t prev_time = 0;
+ int total = 0;
+
+ while (1) {
+ BBEvent event;
+
+ if (trace->ReadBB(&event))
+ break;
+ int bb_diff = event.bb_num - prev_bb_num;
+ //int time_diff = event.time - prev_time;
+ //printf("bb_num: %llu prev: %llu, diff: %d\n",
+ // event.bb_num, prev_bb_num, bb_diff);
+ prev_bb_num = event.bb_num;
+ prev_time = event.time;
+
+ bb_diff += kMaxHistEntries2;
+ if (bb_diff < 0)
+ underflow += 1;
+ else if (bb_diff >= kMaxHistEntries)
+ overflow += 1;
+ else
+ hist[bb_diff] += 1;
+ total += 1;
+ }
+
+ int sum = 0;
+ double sum_per = 0;
+ double per = 0;
+ for (int ii = 0; ii < kMaxHistEntries; ++ii) {
+ if (hist[ii] == 0)
+ continue;
+ per = 100.0 * hist[ii] / total;
+ sum += hist[ii];
+ sum_per = 100.0 * sum / total;
+ printf(" %4d: %6d %6.2f %6.2f\n", ii - kMaxHistEntries2, hist[ii], per, sum_per);
+ }
+ per = 100.0 * underflow / total;
+ printf("under: %6d %6.2f\n", underflow, per);
+ per = 100.0 * overflow / total;
+ printf("over: %6d %6.2f\n", overflow, per);
+ printf("total: %6d\n", total);
+ return 0;
+}