some more size/speed optimizations

src/basic/engine_editor/find_line_38K_60K.s

@@ -19,9 +19,8 @@ find_line_from_current:
 
 	// Check if line is not empty
 
-	jsr peek_line_pointer_null_check
+	jsr is_line_pointer_null
-	bcc find_line_fail
+	beq find_line_fail
-
 
 	// Fetch the high byte of line number and compare
 	ldy #$03
@@ -62,8 +61,8 @@ find_line_next:
 
 	// Advance to the next line
 
-	jsr peek_line_pointer_null_check
+	jsr is_line_pointer_null
-	bcc find_line_fail                           // branch in no more lines exist
+	beq find_line_fail                           // branch in no more lines exist
 
 	ldy #$00
 

src/basic/engine_editor/find_line_46K_50K.s

@@ -25,8 +25,8 @@ find_line_from_current:
 
 	// Check if line is not empty
 
-	jsr find_line_null_ptr_check       // we can't use 'peek_line_pointer_null_check', it maps out/in the BASIC ROM
+	jsr find_line_null_ptr_check       // we can't use 'is_line_pointer_null', it maps out/in the BASIC ROM
-	beq_16 remap_BASIC_sec_rts         // search failed if there is no program
+	beq remap_BASIC_sec_rts            // search failed if there is no program
 
 	// Fetch the high byte of line number and compare
 
@@ -35,7 +35,7 @@ find_line_from_current:
 
 	cmp LINNUM+1
 	beq !+
-	bcs_16 remap_BASIC_sec_rts         // search failed if line number too high
+	bcs remap_BASIC_sec_rts            // search failed if line number too high
 	bne find_line_next
 !:
 	// Fetch the low byte of line number and compare
@@ -44,16 +44,16 @@ find_line_from_current:
 	lda (OLDTXT),y
 
 	cmp LINNUM+0
-	beq_16 remap_BASIC_clc_rts
+	beq remap_BASIC_clc_rts
-	bcs_16 remap_BASIC_sec_rts        // search failed if line number too high
+	bcs remap_BASIC_sec_rts           // search failed if line number too high
 	bne find_line_next
 
 find_line_next:
 
 	// Advance to the next line
 
-	jsr find_line_null_ptr_check       // we can't use 'peek_line_pointer_null_check', it maps out/in the BASIC ROM
+	jsr find_line_null_ptr_check       // we can't use 'is_line_pointer_null', it maps out/in the BASIC ROM
-	beq_16 remap_BASIC_sec_rts         // search failed if no more line exists
+	beq remap_BASIC_sec_rts            // search failed if no more line exists
 
 	ldy #$00
 	lda (OLDTXT),y
@@ -83,4 +83,20 @@ find_line_null_ptr_check:
 	rts
 
 
+remap_BASIC_clc_rts:
+
+	lda #$27
+	sta CPU_R6510
+
+	clc
+	rts
+
+remap_BASIC_sec_rts:
+
+	lda #$27
+	sta CPU_R6510
+
+	sec
+	rts
+
 #endif

src/basic/engine_runtime/execute_line_statements.s

@@ -189,9 +189,8 @@ execute_line:
 
 	// Check if pointer is null, if so, we are at the end of the program
 
-	ldy #0
+	jsr is_line_pointer_null
-	jsr peek_line_pointer_null_check
+	beq_16 shell_main_loop             // branch if end of program reached
-	bcc_16 shell_main_loop             // branch if end of program reached
 
 	// Skip pointer and line number to get address of first statement
 

src/basic/engine_runtime/is_line_pointer_null_38K_60K.s

@@ -2,13 +2,12 @@
 // #LAYOUT# *   BASIC_0 #TAKE
 // #LAYOUT# *   *       #IGNORE
 
-// Return C=1 if a pointer in BASIC memory space is NULL, else C=0
+// Return pointer in BASIC memory space status in Z flag
-// X = ZP pointer to check
 
 
 #if CONFIG_MEMORY_MODEL_38K || CONFIG_MEMORY_MODEL_60K
 
-peek_line_pointer_null_check:
+is_line_pointer_null:
 
 	// Check the pointer
 
@@ -32,16 +31,7 @@ peek_line_pointer_null_check:
 	lda (OLDTXT),y
 #endif
 
-	bne !+
-
-	// Pointer is NULL
-
-	clc
-	rts
 !:
-	// Pointer not NULL
-
-	sec
 	rts
 
 #endif

src/basic/engine_runtime/is_line_pointer_null_46K_50K.s

@@ -4,13 +4,12 @@
 
 // This has to go $E000 or above - routine below banks out the main BASIC ROM!
 
-// Return C=1 if a pointer in BASIC memory space is NULL, else C=0
+// Return pointer in BASIC memory space status in Z flag
-// X = ZP pointer to check
 
 
 #if CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
 
-peek_line_pointer_null_check:
+is_line_pointer_null:
 
 	// Unmap BASIC lower ROM
 
@@ -25,28 +24,14 @@ peek_line_pointer_null_check:
 	
 	dey
 	lda (OLDTXT),y
-	bne !+                   // branch if pointer not NULL
-
-	// Pointer is NULL
-
-	// FALLTROUGH
-
-remap_BASIC_clc_rts:
-
-	lda #$27
-	sta CPU_R6510
-
-	clc
-	rts
 !:
-	// Pointer not NULL
 
-remap_BASIC_sec_rts:
+	// Restore memory mapping and quit
 
+	php
 	lda #$27
 	sta CPU_R6510
-
+	plp
-	sec
 	rts
 
 #endif