GOTO command got performance optimization

src/basic/basic_commands/cmd_run_goto.s

@@ -6,32 +6,83 @@
 cmd_run:
 
 	// RUN clears all variables
+
 	jsr do_clr
 
-cmd_goto:
+	// Initialize OLDTXT pointer, disable Kernal messages
 
-	// XXX optimize this: deduplicate last part (and init_oldtxt) with load/verify,
+	jsr init_oldtxt
-	// if line number greater than current line - find line backwards
-
-	// Disable Kernal messages
 	lda #$00
 	jsr JSETMSG
 
-	// Reset line pointer to first line of program.
+	// Check if we have any paramenters
-	jsr init_oldtxt
 
 	jsr is_end_of_statement
-	bcs !+
+	bcs cmd_run_goto_launch
+
+	// FALLTROUGH
+
+cmd_goto:
+
+	// GOTO requires line number
 
 	jsr fetch_line_number
 	bcs_16 do_SYNTAX_error
-	jsr find_line
+
-	bcc !+
+	// Check for direct mode
-	// Line does not exist, so report error
+
-	jmp do_UNDEFD_STATEMENT_error
+	lda CURLIN+1
+	bmi cmd_goto_direct
+
+	// Not a direct mode - compare desired line number (LINNUM) with the current one (CURLIN)
+
+	lda LINNUM+1
+	cmp CURLIN+1
+	bne !+
+	lda LINNUM+0
+	cmp CURLIN+0
 !:
+	// If desired line number is lower - search line number from start
+
+	bcc cmd_goto_from_start
+
+	// Else - search from the current line
+
+	jsr find_line_from_current
+
+#if HAS_OPCODES_65C02
+	bra cmd_goto_check
+#else
+	jmp cmd_goto_check
+#endif
+
+cmd_goto_direct:
+
+	// Disable Kernal messages
+
+	lda #$00
+	jsr JSETMSG
+
+	// FALLTROUGH
+
+cmd_goto_from_start:
+
+	// Direct mode - find the line from the beginning
+
+	jsr find_line_from_start
+
+	// FALLTROUGH
+
+cmd_goto_check:
+
+	bcs_16 do_UNDEFD_STATEMENT_error
+
+	// FALLTROUGH
+
+cmd_run_goto_launch:
+
 	// Run it!
-	
+
 	pha
 	pha
 	jmp execute_line

src/basic/editor/find_line.s

@@ -3,23 +3,17 @@
 // #LAYOUT# *   *       #IGNORE
 
 
-// Find the BASIC line with number LINNUM
+// Find the BASIC line with number in LINNUM
-
-// XXX it should be possible to start from the current line (OLDTXT), or from the startup,
-//     depending on the current and target line number
 
 
-find_line:
+find_line_from_start:
 
 	// Get pointer to start of BASIC text
-	lda TXTTAB+0
+	jsr init_oldtxt
-	sta OLDTXT+0
-	lda TXTTAB+1
-	sta OLDTXT+1
 
 	// FALLTROUGH
 
-find_line_loop:
+find_line_from_current:
 
 	// Check if line is not empty
 
@@ -100,9 +94,9 @@ find_line_next:
 	sta OLDTXT+0
 
 #if HAS_OPCODES_65C02
-	bra find_line_loop
+	bra find_line_from_current
 #else
-	jmp find_line_loop
+	jmp find_line_from_current
 #endif
 
 find_line_fail:

src/basic/editor/insert_line.s

@@ -13,7 +13,7 @@
 
 insert_line:
 
-	// ASSUMES find_line has been called to set the insert point.
+	// ASSUMES find_line_from_start has been called to set the insert point.
 
 	// jsr printf
 	// .text "INSERTING LINE AT $"

src/basic/editor/shell.s

@@ -169,12 +169,12 @@ shell_add_delete_line:
 	jsr update_VARTAB_do_clr
 
 	// Check if line already present
-	jsr find_line
+	jsr find_line_from_start
 	bcs !+
 
 	// Line already present - delete it
 	jsr delete_line
-	jsr find_line                                // refresh OLDTXT
+	jsr find_line_from_start                     // refresh OLDTXT
 !:
 	// Insert new line if non-zero length, i.e., that
 	// we are not just deleting the line.