From: Frank Mori Hess <fmhess@speakeasy.net>
Date: Fri, 2 Jan 2004 01:16:00 +0000 (+0000)
Subject: doing a retry for the preload write is useless, since the command
X-Git-Tag: r0_7_22~103
X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=998c091e1e3376da29e46c1efd141c11224b3024;p=comedilib.git

doing a retry for the preload write is useless, since the command
hasn't started yet.  Print a useful error message and exit instead.
---

diff --git a/demo/ao_waveform.c b/demo/ao_waveform.c
index a37eaa9..0e9f6bc 100644
--- a/demo/ao_waveform.c
+++ b/demo/ao_waveform.c
@@ -178,16 +178,18 @@ int main(int argc, char *argv[])
 	}
 
 	dds_output(data,BUF_LEN);
-	n=BUF_LEN*sizeof(sampl_t);
-	while(n>0){
-		m=write(comedi_fileno(dev),(void *)data+(BUF_LEN*sizeof(sampl_t)-n),n);
-		if(m<0){
-			perror("write");
-			exit(0);
-		}
-		printf("m=%d\n",m);
-		n-=m;
+	n = BUF_LEN * sizeof(sampl_t);
+	m = write(comedi_fileno(dev), (void *)data, n);
+	if(m < 0){
+		perror("write");
+		exit(1);
+	}else if(m < n)
+	{
+		fprintf(stderr, "failed to preload output buffer with %i bytes, is it too small?\n"
+			"See the --write-buffer option of comedi_config\n", n);
+		exit(1);
 	}
+	printf("m=%d\n",m);
 
 	ret = comedi_internal_trigger(dev, subdevice, 0);
 	if(ret<0){