--- buffer-1.19/buffer.c	2015-12-06 22:36:43.364143317 +0000(B
+++ /tmp/buffer-new.c	2015-12-06 22:36:26.001894230 +0000(B
@@ -255,6 +255,7 @@(B
 int reader_pid	= 0;
 int free_shm	= 1;
 int percent	= 0;
+int min_percent	= 0;(B
 int debug	= 0;
 int Zflag	= 0;
 int writer_status = 0;
@@ -385,6 +386,16 @@(B
 			if( debug )
 				fprintf( stderr, "percent set to %d\n", percent );
 			break;
+		case 'P':	/* min percent to maintain in the buffer */(B
+			min_percent = atoi( optarg );(B
+(B
+			if( (min_percent < 0) || (100 < min_percent) ){(B
+				fprintf( stderr, "min_percent %d out of range\n", min_percent );(B
+				byee( -1 );(B
+			}(B
+			if( debug )(B
+				fprintf( stderr, "min_percent set to %d\n", min_percent );(B
+			break;(B
 		case 'z':
 			zflag++;
 			/* FALL THRU */
@@ -397,7 +408,7 @@(B
 			}
 			break;
 		default:
-			fprintf( stderr, "Usage: %s [-B] [-t] [-S size] [-m memsize] [-b blocks] [-p percent] [-s blocksize] [-u pause] [-i infile] [-o outfile] [-z size] [-Z] [-d]\n",(B
+			fprintf( stderr, "Usage: %s [-B] [-t] [-S size] [-m memsize] [-b blocks] [-p percent] [-P min_percent] [-s blocksize] [-u pause] [-i infile] [-o outfile] [-z size] [-Z] [-d]\n",(B
 				progname );
 			fprintf( stderr, "-B = blocked device - pad out last block\n" );
 			fprintf( stderr, "-t = show total amount written at end\n" );
@@ -405,6 +416,7 @@(B
 			fprintf( stderr, "-m size = size of shared mem chunk to grab\n" );
 			fprintf( stderr, "-b num = number of blocks in queue\n" );
 			fprintf( stderr, "-p percent = don't start writing until percent blocks filled\n" );
+			fprintf( stderr, "-P min_percent = min number of blocks to keep in the buffer\n" );(B
 			fprintf( stderr, "-s size = size of a block\n" );
 			fprintf( stderr, "-u usecs = microseconds to sleep after each write\n" );
 			fprintf( stderr, "-i infile = file to read from\n" );
@@ -421,6 +433,11 @@(B
 		byee( -1 );
 	}
 
+        if (min_percent > percent) {(B
+		fprintf( stderr, "min_percent > percent, aborting!\n" );(B
+		byee( -1 );(B
+	}(B
+(B
 	if (zflag) showevery = blocksize;
 
 	/* If -b was not given try and work out the max buffer size */
@@ -748,12 +765,14 @@(B
 {
 	int filled = 0;
 	int maxfilled = (blocks * percent) / 100;
+	int minfilled = (blocks * min_percent) / 100;(B
 	int first_block = 0;
 
 	if( debug )
-		fprintf( stderr, "\tW: Entering writer\n blocks = %d\n maxfilled = %d\n",(B
+		fprintf( stderr, "\tW: Entering writer\n blocks = %d\n"(B
+                                 " maxfilled = %d\n minfilled = %d\n",(B
 			blocks,
-			maxfilled );(B
+			maxfilled, minfilled );(B
 
 	while( 1 ){
 		if( !filled )
@@ -765,10 +784,10 @@(B
 		filled++;
 		if( debug > 1 )
 			fprintf( stderr, "W: filled = %d\n", filled );
-		if( filled >= maxfilled ){(B
+		if( filled >= maxfilled && filled > minfilled ){(B
 			if( debug > 1 )
 				fprintf( stderr, "W: writing\n" );
-			write_blocks_to_stdout( filled, first_block );(B
+			write_blocks_to_stdout( filled - minfilled, first_block );(B
 			filled = 0;
 		}
 	}