better example code

main.c

@@ -6,16 +6,23 @@
 
 // ------- TESTING ----------
 
+static void send_cmd(const char *cmd)
+{
+	printf("\n> %s\n", cmd);
+	scpi_handle_string(cmd);
+}
+
 int main()
 {
-	scpi_handle_string("*IDN?\n");
+	send_cmd("*IDN?\n"); // builtin commands..
-	scpi_handle_string("*SRE 4\n");
+	send_cmd("*SRE 4\n"); // enable SRQ on error
-	scpi_handle_string("FOO:BAR:BAZ\n");
+	send_cmd("FOO:BAR:BAZ\n"); // invalid command causes error
-	scpi_handle_string("SYST:ERR:COUNT?\n");
+	send_cmd("SYST:ERR:COUNT?\n"); // error subsystem
-	scpi_handle_string("SYST:ERR?\n");
+	send_cmd("SYST:ERR:NEXT?;COUNT?;NEXT?\n"); // semicolon works according to spec
-	scpi_handle_string("SYST:ERR?\n");
+	send_cmd("DATA:BLOB #216abcdefghijklmnop\n"); // binary data block
-	scpi_handle_string("DATA:BLOB #216abcdefghijklmnop\n");
+
-	scpi_handle_string("SYST:ERR?\n");
+	send_cmd("APPLY:SINE 50, 1.0, 2.17\n"); // floats
+	send_cmd("DISP:TEXT \"Hello world\"\n"); // string
 }
 
 
@@ -35,15 +42,20 @@ const char *scpi_device_identifier(void)
 
 void scpi_service_request_impl(void)
 {
-	printf("[SRQ]\n");
+	// NOTE: Actual instrument should send SRQ event somehow
+
+	printf("[SRQ] - error: ");
+	char buf[256];
+	scpi_read_error_noremove(buf); // show error message (for debug)
+	printf("%s\n", buf);
 }
 
 
-// ---- COMMANDS ----
+// ---- INSTRUMENT COMMANDS ----
 
 void cmd_APPL_SIN_cb(const SCPI_argval_t *args)
 {
-	printf("cb  APPLy:SINe %d, %f, %f\n", args[0].INT, args[0].FLOAT, args[0].FLOAT);
+	printf("cb APPLy:SINe %d, %f, %f\n", args[0].INT, args[1].FLOAT, args[2].FLOAT);
 }
 
 
@@ -56,16 +68,17 @@ void cmd_DISP_TEXT_cb(const SCPI_argval_t *args)
 
 void cmd_DATA_BLOB_cb(const SCPI_argval_t *args)
 {
-	printf("cb  DATA:BLOB <%d>\n", args[1].BLOB_LEN);
+	printf("cb DATA:BLOB <%d>\n", args[0].BLOB_LEN);
 }
 
 
 void cmd_DATA_BLOB_data(const uint8_t *bytes)
 {
-	printf("blob item: %s\n", bytes);
+	printf("binary data: \"%s\"\n", bytes);
 }
 
 
+// Command definition (mandatory commands are built-in)
 const SCPI_command_t scpi_commands[] = {
 	{
 		.levels = {"APPLy", "SINe"},

source/scpi_errors.c

@@ -5,12 +5,104 @@
 #include <string.h>
 
 #include "scpi_errors.h"
+#include "scpi_regs.h"
+
+#define ERR_QUEUE_LEN 4
+#define MAX_ERROR_LEN 255
+
+// --- queue impl ---
+
+
+static struct {
+	char queue[ERR_QUEUE_LEN][MAX_ERROR_LEN + 1];
+	int8_t r_pos;
+	int8_t w_pos;
+	int8_t count; // signed for backtracking
+} erq;
+
+
+void scpi_add_error(SCPI_error_t errno, const char *extra)
+{
+	bool added = true;
+	if (erq.count >= ERR_QUEUE_LEN) {
+		errno = E_DEV_QUEUE_OVERFLOW;
+		extra = NULL;
+		added = false; // replaced only
+
+		// backtrack
+		erq.w_pos--;
+		erq.count--;
+		if (erq.w_pos < 0) {
+			erq.w_pos = ERR_QUEUE_LEN - 1;
+		}
+	}
+
+	scpi_error_string(erq.queue[erq.w_pos], errno, extra);
+
+	erq.w_pos++;
+	erq.count++;
+	if (erq.w_pos >= ERR_QUEUE_LEN) {
+		erq.w_pos = 0;
+	}
+
+	scpi_status_update();
+}
+
+
+void scpi_read_error_noremove(char *buf)
+{
+	if (erq.count == 0) {
+		scpi_error_string(buf, E_NO_ERROR, NULL);
+		return;
+	}
+
+	strcpy(buf, erq.queue[erq.r_pos]);
+}
+
+
+void scpi_read_error(char *buf)
+{
+	if (erq.count == 0) {
+		scpi_error_string(buf, E_NO_ERROR, NULL);
+		return;
+	}
+
+	strcpy(buf, erq.queue[erq.r_pos++]);
+	erq.count--;
+
+	if (erq.r_pos >= ERR_QUEUE_LEN) {
+		erq.r_pos = 0;
+	}
+
+	scpi_status_update();
+}
+
+
+void scpi_clear_errors(void)
+{
+	erq.r_pos = 0;
+	erq.w_pos = 0;
+	erq.count = 0;
+
+	scpi_status_update();
+}
+
+
+uint8_t scpi_error_count(void)
+{
+	return erq.count;
+}
+
+
+// ---- table ----
+
 
 typedef struct {
 	const int16_t errno;
 	const char *msg;
 } SCPI_error_desc;
 
+
 static const SCPI_error_desc error_table[] = {
 	{ 0, "No error"},
 	{ -100, "Command error"},
@@ -184,3 +276,4 @@ void scpi_error_string(char *buffer, SCPI_error_t errno, const char *extra)
 
 	sprintf(buffer, "\""); // "
 }
+

source/scpi_errors.h

@@ -132,6 +132,7 @@ typedef enum {
 /** Get SCPI error message (alone) */
 const char *scpi_error_message(SCPI_error_t errno);
 
+
 /**
  * Get SCPI error string for reporting:
  * <code>,"<message>[; <extra>]"
@@ -139,3 +140,24 @@ const char *scpi_error_message(SCPI_error_t errno);
  * extra can be NULL to skip the optional part.
  */
 void scpi_error_string(char *buffer, SCPI_error_t errno, const char *extra);
+
+
+/** Add error to the error queue */
+void scpi_add_error(SCPI_error_t errno, const char *extra);
+
+
+/** Get number of errors in the error queue */
+uint8_t scpi_error_count(void);
+
+
+/**
+ * Read and remove one entry from the error queue.
+ * Returns 0,"No error" if the queue is empty.
+ *
+ * The entry is copied to the provided buffer, which must be 256 chars long.
+ */
+void scpi_read_error(char *buf);
+
+
+/** Read error, do not remove from queue */
+void scpi_read_error_noremove(char *buf);

source/scpi_parser.c

@@ -11,8 +11,6 @@
 #include "scpi_regs.h"
 
 // Config
-#define ERR_QUEUE_LEN 4
-#define MAX_ERROR_LEN 255
 #define MAX_CHARBUF_LEN 255
 
 
@@ -52,11 +50,6 @@ typedef enum {
 
 /** Parser internal state struct */
 static struct {
-	char err_queue[ERR_QUEUE_LEN][MAX_ERROR_LEN + 1];
-	int8_t err_queue_r;
-	int8_t err_queue_w;
-	int8_t err_queue_used; // signed for backtracking
-
 	parser_state_t state; // current parser internal state
 
 	// string buffer, chars collected here until recognized
@@ -140,70 +133,7 @@ void scpi_send_string(const char *message)
 	scpi_send_byte_impl('\n');
 }
 
-
+// ------- Error shortcuts ----------
-// ------------------- ERROR QUEUE ---------------------
-
-void scpi_add_error(SCPI_error_t errno, const char *extra)
-{
-	bool added = true;
-	if (pst.err_queue_used >= ERR_QUEUE_LEN) {
-		errno = E_DEV_QUEUE_OVERFLOW;
-		extra = NULL;
-		added = false; // replaced only
-
-		// backtrack
-		pst.err_queue_w--;
-		pst.err_queue_used--;
-		if (pst.err_queue_w < 0) {
-			pst.err_queue_w = ERR_QUEUE_LEN - 1;
-		}
-	}
-
-	scpi_error_string(pst.err_queue[pst.err_queue_w], errno, extra);
-
-	pst.err_queue_w++;
-	pst.err_queue_used++;
-	if (pst.err_queue_w >= ERR_QUEUE_LEN) {
-		pst.err_queue_w = 0;
-	}
-
-	scpi_status_update();
-}
-
-
-void scpi_read_error(char *buf)
-{
-	if (pst.err_queue_used == 0) {
-		scpi_error_string(buf, E_NO_ERROR, NULL);
-		return;
-	}
-
-	strcpy(buf, pst.err_queue[pst.err_queue_r++]);
-	pst.err_queue_used--;
-
-	if (pst.err_queue_r >= ERR_QUEUE_LEN) {
-		pst.err_queue_r = 0;
-	}
-
-	scpi_status_update();
-}
-
-
-void scpi_clear_errors(void)
-{
-	pst.err_queue_r = 0;
-	pst.err_queue_w = 0;
-	pst.err_queue_used = 0;
-
-	scpi_status_update();
-}
-
-
-uint8_t scpi_error_count(void)
-{
-	return pst.err_queue_used;
-}
-
 
 static void err_no_such_command()
 {

source/scpi_parser.h

@@ -40,7 +40,7 @@ typedef union {
  */
 typedef struct {
 	// levels MUST BE FIRST!
-	const char levels[SCPI_MAX_LEVEL_COUNT][SCPI_MAX_CMD_LEN+2]; // up to 4 parts (+? and \0)
+	const char levels[SCPI_MAX_LEVEL_COUNT][SCPI_MAX_CMD_LEN + 2]; // up to 4 parts (+? and \0)
 
 	// called when the command is completed. BLOB arg must be last in the argument list,
 	// and only the first part is collected.
@@ -84,20 +84,6 @@ void scpi_handle_byte(const uint8_t b);
 void scpi_handle_string(const char* str);
 
 
-/** Add error to the error queue */
-void scpi_add_error(SCPI_error_t errno, const char *extra);
-
-/** Get number of errors in the error queue */
-uint8_t scpi_error_count(void);
-
-/**
- * Read and remove one entry from the error queue.
- * Returns 0,"No error" if the queue is empty.
- *
- * The entry is copied to the provided buffer, which must be 256 chars long.
- */
-void scpi_read_error(char *buf);
-
 /** Discard the rest of the currently processed blob */
 void scpi_discard_blob(void);