From 41957bd369ef39697aba39d5b60297bbbbf44f7f Mon Sep 17 00:00:00 2001
From: "B. Watson" <yalhcru@gmail.com>
Date: Fri, 23 Jul 2021 14:24:11 -0400
Subject: Add fractional microsecond support
---
Makefile | 3 +++
slowbaud.c | 20 +++++++++++++++++++-
2 files changed, 22 insertions(+), 1 deletion(-)
diff --git a/Makefile b/Makefile
index 084bee4..3cd67e0 100644
--- a/Makefile
+++ b/Makefile
@@ -16,6 +16,9 @@ $(PROJ).1: $(PROJ).rst
README.txt: $(PROJ).1
man ./$(PROJ).1 | sed 's,_\010,,' > README.txt
+test: all
+ sh test.sh
+
# Don't remove the man page or README here, it's in git.
clean:
rm -f $(PROJ) core *.o
diff --git a/slowbaud.c b/slowbaud.c
index 63a8a3b..e0ad048 100644
--- a/slowbaud.c
+++ b/slowbaud.c
@@ -41,6 +41,13 @@ struct timeval tv;
struct itimerval itv, itv_disarm;
sigset_t sigmask;
+#define FRACTIONAL_USEC
+
+#ifdef FRACTIONAL_USEC
+#define FRAC_US_DENOM 100
+int frac_us_num;
+#endif
+
#define NOW_USEC() ( (gettimeofday(&tv, NULL)), tv.tv_sec * 1000000L + tv.tv_usec )
void die(const char *msg) {
@@ -77,6 +84,10 @@ void slow_write(int outfd, char c) {
target = NOW_USEC() + interval;
+#ifdef FRACTIONAL_USEC
+ if((random() % FRAC_US_DENOM) < frac_us_num) target++;
+#endif
+
write(outfd, &c, 1);
outbytes++;
sigwait(&sigmask, &j);
@@ -85,7 +96,8 @@ void slow_write(int outfd, char c) {
now = NOW_USEC();
if(now > target) {
overslept = now - target;
- if(overslept < interval) {
+ if(overslept < itv.it_interval.tv_usec) {
+ // fprintf(stderr, "overslept %luus\n", overslept);
itv.it_interval.tv_usec -= overslept;
itv.it_value.tv_usec = itv.it_interval.tv_usec;
}
@@ -287,6 +299,12 @@ int main(int argc, char **argv) {
interval = (unsigned long)(1000000.0L / ((double)bps / 10.0L));
if(debug) fprintf(stderr, "interval %ld us\n", interval);
+#ifdef FRACTIONAL_USEC
+ frac_us_num = (double)FRAC_US_DENOM * ((1000000.0L / ((double)bps / 10.0L) - interval));
+ fprintf(stderr, "%d %d\n", interval, frac_us_num);
+ // srandom(NOW_USEC());
+#endif
+
if(*argv && argv[0][0] == '-' && argv[0][1] == '-' && !argv[0][2]) {
if(debug) fprintf(stderr, "skipping -- argument\n");
argv++, argc--;
--
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