blocking read is not blocking

README.md

@@ -12,6 +12,11 @@ Pour en savoir plus sur ce passionnant projet, il y a le canal IRC
 `#tetalab` sur le réseau Freenode et/ou les rencontres du mercredi
 soir au DD2, à Mixart-Myrys.
 
+# WTF status
+
+Le `read` bloquant ne bloque pas. Ça craint grave.
+
+
 
 
 

serial/README.md

@@ -22,6 +22,12 @@ par le professeur Cispeo.
 
 Un petit exemple ?
 
+Oui, voilà. À ce jour (20 déc. 2018), on va dire que ça ne marche pas.
+Il faut dire que les `serial devices` ont toujours étés un peu le
+domaine de la magie noire. Mais quand même, coincer sur un `read` qui
+ne bloque pas, c'est un peu ironique.
+ 
+
 
 
 

serial/serial.c

@@ -1,7 +1,9 @@
 
 #include <stdio.h>
 #include  <stdlib.h>
+#include  <errno.h>
 #include  <sys/select.h>
+#include  <string.h>
 #include <unistd.h>			//Used for UART
 #include <fcntl.h>			//Used for UART
 #include <termios.h>		//Used for UART
@@ -60,13 +62,15 @@ fprintf(stderr, "%s ( %s %d )\n", __func__, port, baudrate);
 // shall not cause the terminal device to become the controlling terminal
 // for the process.
 
-uart0 = open(port, O_RDWR | O_NOCTTY);
+uart0 = open(port, O_RDONLY | O_NOCTTY);
-if (uart0== -1)
+if (uart0 < 0)
 	{
 	perror("unable to open uart ");
 	return -1;
 	}
 
+return uart0;		/* WTF ??? */
+	
 // CONFIGURE THE UART
 // The flags defined in /usr/include/termios.h -
 // see http://pubs.opengroup.org/onlinepubs/007908799/xsh/termios.h.html
@@ -87,6 +91,9 @@ baudbits = baudrate2const(baudrate);
 #if DEBUG_LEVEL
 fprintf(stderr, "%d -> 0x%04x\n", baudrate, baudbits);
 #endif
+
+memset(&options, 0, sizeof(options));
+
 tcgetattr(uart0, &options);
 options.c_cflag = baudbits | CS8 | CLOCAL | CREAD;	//<Set baud rate
 options.c_iflag = IGNPAR;
@@ -100,16 +107,20 @@ return uart0;
 /* -------------------------------------------------------------------- */
 /*
  *	this function have NO timeout !
+ *	blocking read is not blocking, wtf ?
  */
 int getbyte(int fd)
 {
 unsigned char   byte;
 int             foo;
 
+byte = 0;
+
 foo = read(fd, &byte, 1);
 if (1 != foo)
         {
-        perror("read a byte");
+	fprintf(stderr, "byte %d rd %d errno %d\n",
+					byte, foo, errno);
         return -1;
         }
 return (int)byte;
@@ -126,9 +137,8 @@ int		retval;
 
 timeout.tv_sec  = to_ms / 1000;
 timeout.tv_usec = (to_ms % 1000) * 1000;
-
 #if DEBUG_LEVEL
-fprintf(stderr, "timeout %6d is %4ld %6ld\n", to_ms,
+fprintf(stderr, "timeout %6d is %4ld.%6ld\n", to_ms,
 				timeout.tv_sec, timeout.tv_usec);
 #endif
 
@@ -136,38 +146,37 @@ FD_ZERO   (&rfds);
 FD_SET    (fd, &rfds);
 
 retval = select(1, &rfds, NULL, NULL, &timeout);
-
 #if DEBUG_LEVEL
 fprintf(stderr, "%s : select -> %d\n", __func__, retval);
 #endif
 
-retval = retval < 0 ? -1 : retval;
-
 switch (retval) {
 
 	case -1:
 		fprintf(stderr, "omg ?\n");
-		byte = -1;
+		retval = -1;
 		break;
 
 	case 0:
 		fprintf(stderr, "timeout\n");
-		byte = -99;
+		retval = -99;
 		break;
 
 	default:
+		fprintf(stderr, "%s default -> %d\n", __func__, retval);
 		if (retval==fd) {
 			read(fd, &byte, 1);
 			fprintf(stderr, "got 0x%02x\n", byte);
+			retval = byte;
 			}
 		else	{
 			fprintf(stderr, "%d bad fd ?\n", retval);
-			byte = -3;
+			retval = -3;
 			}
 		break;
 	}
 
-return byte;
+return retval;
 }
 /* -------------------------------------------------------------------- */
 /* timeout is in milliseconds */
@@ -195,15 +204,21 @@ for(;;)	{
 		retval = curpos;
 		}
 
-	
+	if (curpos < szm) {			/* ya de la place */
-
+		where[curpos] = byte;
+		curpos++;
+		}
+	else	{				/* oups overflow */
+		retval = -6;
+		break;
+		}
 
 	}
 
 fprintf(stderr, "%s -> '%s'\n", __func__, where);
 
 
-return -666;
+return retval;
 }
 /* -------------------------------------------------------------------- */
 

serial/serial.h

@@ -6,7 +6,7 @@
 
 int prepare_UART(char *port, int bauds);
 
-int getbyte(int fd);
+int getbyte(int fd);			/* really brotched func */
 
 
 /* timeout is exprimed in milliseconds. */

serial/t.c

@@ -1,28 +1,36 @@
 
 
 #include  <stdio.h>
+#include  <stdlib.h>
 #include  <time.h>
 
 #include  "serial.h"
 
+int	verbosity;
+
 int main (int argc, char *argv[])
 {
-int	serial_in;
+int		serial_in;
-int	byte, foo, to;
+int		byte;
 
-serial_in = prepare_UART("/dev/ttyS0", 9600);
+serial_in = prepare_UART("/dev/ttyACM0", 9600);
 fprintf(stderr, "prepare uart -> %d\n", serial_in);
 
-for (foo=0; foo<20; foo++) {
+if (serial_in < 0) {
-	to = (foo+1) * 666;
+	exit(1);
-	byte = getbyte_to(serial_in, to);
+	}
+
+for (;;) {
+
+	byte = getbyte(serial_in);
+
 	if (byte < 0) {
 		fprintf(stderr, "get byte : err is %d\n", byte);
 		}
-	// XXX else	{
+	else	{
-		printf("%9ld   %6d   %6d    %02x\n",
+		printf("%9ld  %02x/%d\n",
-				time(NULL), foo, to, byte);
+			time(NULL), byte, byte);
-	// XXX	}
+		}
 	}
 
 return 0;

simulator/send-random/send-random.ino

@@ -0,0 +1,55 @@
+/*
+ *  simulateur de telemesure automate
+ */
+
+/* -------------------------------------------------- */
+
+#define NBVAL   4
+
+int   values[NBVAL];
+
+/* -------------------------------------------------- */
+void setup() {
+  int   foo;
+  Serial.begin(9600);
+  pinMode(LED_BUILTIN, OUTPUT);
+  for (foo=0; foo<NBVAL; foo++) {
+    values[foo] = 0;
+  }
+}
+/* -------------------------------------------------- */
+void updatevalues(void)
+{
+  int foo;
+  for (foo=0; foo<NBVAL; foo++) {
+    if (rand()%100<33) {
+      values[foo] += (foo + 1);
+      }
+    if (values[foo] > 1023) {
+      values[foo] = rand()%15;
+      }
+  }
+}
+/* -------------------------------------------------- */
+
+void sendvalues(void)
+{
+  int foo;
+
+  Serial.print("X ");
+  for (foo=0; foo<NBVAL; foo++) {
+    Serial.print(" ");
+    Serial.print(values[foo]);
+    }
+  Serial.print("\n");
+}
+/* -------------------------------------------------- */
+
+void loop() {
+  updatevalues();
+  sendvalues();
+  delay(5000);
+}
+
+/* -------------------------------------------------- */
+