Add experimental support for string registers

config.h

@@ -529,6 +529,14 @@ Set to \ref On or 1 to enable experimental support for parameters.
 #define NGC_PARAMETERS_ENABLE On
 #endif
 
+/*! \def STRING_REGISTERS_ENABLE
+\brief
+Set to \ref On or 1 to enable experimental support for string registers.
+*/
+#if !defined STRING_REGISTERS_ENABLE || defined __DOXYGEN__
+#define STRING_REGISTERS_ENABLE Off
+#endif
+
 /*! \def NGC_N_ASSIGN_PARAMETERS_PER_BLOCK
 \brief
 Maximum number of parameters allowed in a block.

core_handlers.h

@@ -133,6 +133,8 @@ typedef bool (*write_tool_data_ptr)(tool_data_t *tool_data);
 typedef bool (*read_tool_data_ptr)(tool_id_t tool_id, tool_data_t *tool_data);
 typedef bool (*clear_tool_data_ptr)(void);
 
+typedef char* (*on_string_substitution_ptr)(char* input, char** output);
+
 typedef struct {
     uint32_t n_tools;
     tool_data_t *tool;          //!< Array of tool data, size _must_ be n_tools + 1
@@ -244,6 +246,7 @@ typedef struct {
     on_set_axis_setting_unit_ptr on_set_axis_setting_unit;
     on_gcode_message_ptr on_gcode_message;              //!< Called on output of message parsed from gcode. NOTE: string pointed to is freed after this call.
     on_gcode_message_ptr on_gcode_comment;              //!< Called when a plain gcode comment has been parsed.
+    on_string_substitution_ptr on_string_substitution;  //!< Called when something wants to process a string for param substitution or similar.
     on_tool_selected_ptr on_tool_selected;              //!< Called prior to executing M6 or after executing M61.
     on_tool_changed_ptr on_tool_changed;                //!< Called after executing M6 or M61.
     on_toolchange_ack_ptr on_toolchange_ack;            //!< Called from interrupt context.

gcode.c

@@ -43,6 +43,10 @@
 #endif
 #endif
 
+#if STRING_REGISTERS_ENABLE
+#include "string_registers.h"
+#endif
+
 // NOTE: Max line number is defined by the g-code standard to be 99999. It seems to be an
 // arbitrary value, and some GUIs may require more. So we increased it based on a max safe
 // value when converting a float (7.2 digit precision) to an integer.
@@ -348,6 +352,10 @@ void gc_init (void)
 
 #if NGC_EXPRESSIONS_ENABLE
     ngc_flowctrl_init();
+    #if STRING_REGISTERS_ENABLE
+    string_registers_init();
+    #endif
+    ngc_expr_init();
 #endif
 #if NGC_PARAMETERS_ENABLE
     ngc_modal_state_invalidate();
@@ -599,14 +607,16 @@ char *gc_normalize_block (char *block, status_code_t *status, char **message)
                         if(message && *message == NULL) {
 #if NGC_EXPRESSIONS_ENABLE
                             if(!strncasecmp(comment, "DEBUG,", 6)) { // Debug message string substitution
-                                if(settings.flags.ngc_debug_out) {
+                                if(settings.flags.ngc_debug_out && grbl.on_string_substitution) {
                                     comment += 6;
-                                    ngc_substitute_parameters(comment, message);
+                                    grbl.on_string_substitution(comment, message);
                                 }
                                 *comment = '\0'; // Do not generate grbl.on_gcode_comment event!
                             } else if(!strncasecmp(comment, "PRINT,", 6)) { // Print message string substitution
-                                comment += 6;
-                                ngc_substitute_parameters(comment, message);
+                                if(grbl.on_string_substitution) {
+                                    comment += 6;
+                                    grbl.on_string_substitution(comment, message);
+                                }
                                 *comment = '\0'; // Do not generate grbl.on_gcode_comment event!
                             } else {
 #endif

ngc_expr.c

@@ -31,6 +31,7 @@
 #include "settings.h"
 #include "ngc_expr.h"
 #include "ngc_params.h"
+#include "core_handlers.h"
 
 #define MAX_STACK 7
 
@@ -75,6 +76,8 @@ typedef enum {
     NGCUnaryOp_Parameter // read setting/setting bit
 } ngc_unary_op_t;
 
+static on_string_substitution_ptr on_string_substitution;
+
 /*! \brief Executes the operations: /, MOD, ** (POW), *.
 
 \param lhs pointer to the left hand side operand and result.
@@ -1061,4 +1064,28 @@ char *ngc_substitute_parameters (char *comment, char **message)
     return *message;
 }
 
+char* onNgcParameterSubstitution(char *input, char **output) {
+    char* result;
+    if (on_string_substitution) {
+        char *intermediate;
+        on_string_substitution(input, &intermediate);
+        result = ngc_substitute_parameters(intermediate, output);
+        free(intermediate);
+    } else {
+        result = ngc_substitute_parameters(input, output);
+    }
+
+    return result;
+}
+
+void ngc_expr_init(void) {
+    static bool init_ok = false;
+
+    if(!init_ok) {
+        init_ok = true;
+        on_string_substitution = grbl.on_string_substitution;
+        grbl.on_string_substitution = onNgcParameterSubstitution;
+    }
+}
+
 #endif

ngc_expr.h

@@ -9,7 +9,6 @@ status_code_t ngc_read_integer_value(char *line, uint_fast8_t *pos, int32_t *val
 status_code_t ngc_read_integer_unsigned (char *line, uint_fast8_t *pos, uint32_t *value);
 status_code_t ngc_read_parameter (char *line, uint_fast8_t *pos, float *value, bool check);
 status_code_t ngc_eval_expression (char *line, uint_fast8_t *pos, float *value);
-/**/
-char *ngc_substitute_parameters (char *comment, char **message);
+void ngc_expr_init(void);
 
 #endif

ngc_flowctrl.c

@@ -297,20 +297,23 @@ void ngc_flowctrl_unwind_stack (vfs_file_t *file)
 
 static status_code_t onGcodeComment (char *comment)
 {
-    uint_fast8_t pos = 6;
-    status_code_t status = Status_OK;
-
     if(!strncasecmp(comment, "ABORT,", 6)) {
-        char *buf = NULL;
-        if(ngc_substitute_parameters(comment + pos, &buf)) {
-            report_message(buf, Message_Error);
-            free(buf);
+        uint_fast8_t pos = 6;
+        if (grbl.on_string_substitution) {
+            char *buf = NULL;
+            if (grbl.on_string_substitution(comment + pos, &buf)) {
+                report_message(buf, Message_Error);
+                free(buf);
+            }
+        } else {
+            report_message(comment + pos, Message_Error);
         }
-        status = Status_UserException;
-    } else if(on_gcode_comment)
-        status = on_gcode_comment(comment);
+        return Status_UserException;
+    } else if(on_gcode_comment) {
+        return on_gcode_comment(comment);
+    }
 
-    return status;
+    return Status_OK;
 }
 
 void ngc_flowctrl_init (void)