Diff: printbuf.c

Revision:

10:716484b1ddb5

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/printbuf.c	Tue Apr 05 18:30:41 2016 +0000
@@ -0,0 +1,65 @@
+/***********************************************************************/
+/*                                                                     */
+/*  printbuf.c:  Low Level print ring buffer  Routines                               */
+/*                                                                     */
+/***********************************************************************/
+#include <stdio.h>
+#include <stdarg.h>
+
+#define CR     0x0D
+#define TEMT 0x40	/* serial COMTX empty */
+extern int write (int file, char * ptr, int len);
+int putchar_buf(int);
+int putcharNB(int);
+
+
+/* Background non-blocking print using ring buffer */
+#define PRNBUFSZ 0x100
+char printbuffer[PRNBUFSZ];
+int prnbuf_count = 0;   /* number of characters in buffer */
+int prnbuf_pos = 0;   /* location to store characters */
+
+
+int printfNB(const char *format, ...)
+{  char buffer[128]; int i;
+	char c;
+	int val;
+  va_list args;     
+  va_start( args, format );
+  val = vsprintf(buffer, format, args );   // print to string using variable arguments
+	for(i = 0; i < 128 && buffer[i]!= '\0'; i++)    // copy string to print buffer
+	{ putcharNB((int)buffer[i]); }
+	return(val);
+}
+
+
+// overload putchar to use non-blocking print to ring buffer instead
+int putcharNB(int c)  {
+  	if (c == '\n') putchar_buf(CR);
+	putchar_buf(c);
+	return(c);	} 
+
+	
+/* routine to print using print ring buffer */
+/* does not block - allows over runs */
+int putchar_buf(int c)
+{
+  if(prnbuf_count >= PRNBUFSZ) return(0);   /* no room - drop character */
+  printbuffer[prnbuf_pos] = c;
+  prnbuf_pos++;
+  prnbuf_count++;   /* need to make uninterruptable? */
+  if(prnbuf_pos > (PRNBUFSZ-1))  prnbuf_pos = 0;   /* wrap index to beginning of
+ buffer */
+  return(c);
+}
+
+
+
+
+int write (int file, char * ptr, int len) {
+  int i;
+
+  for (i = 0; i < len; i++) putcharNB(*ptr++);
+  return len;
+}
+