started work on array element location

src/basic/engine_variables/array_create.s

@@ -10,15 +10,18 @@ array_create:
 	jsr fetch_variable_name
 	bcs_16 do_SYNTAX_error
 
-	// XXX check if the array already exists
+	// Make sure the array does not exist
+
+	jsr find_array
+	bcc_16 do_REDIMD_ARRAY_error
 
 	// Push variable name and FOUR6 on the stack - fetching dimensions might cause
 	// the to be overwritten by the expression parser
 
-	lda VARNAM+0
-	pha
 	lda VARNAM+1
 	pha
+	lda VARNAM+0
+	pha
 	lda FOUR6
 	pha
 
@@ -180,7 +183,7 @@ array_create_store_dims_done:
 	// Restore FOUR6, calculate number of bytes needed for storage
 
 	pla
-	sta FOUR6 // XXX do we need to store this value in FOUR6? is it still needed?
+	sta FOUR6                          // needed by variable fetch routine
 
 	sta __FAC1+3
 	stx __FAC1+4                       // .X is 0 at this point

src/basic/engine_variables/fetch_variable.s

@@ -57,36 +57,8 @@ fetch_variable_find_addr_loop:
 	beq fetch_variable_alocate
 !:
 	// Compare current variable name with searched one
-	// XXX consider creating optimized version for 46K/50K memory models
 
-#if CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
 	jsr helper_cmp_varnam
-#else
-
-	ldy #$00
-
-#if CONFIG_MEMORY_MODEL_60K
-	ldx #<VARPNT
-	jsr peek_under_roms
-#else // CONFIG_MEMORY_MODEL_38K
-	lda (VARPNT),y
-#endif
-
-	cmp VARNAM+0
-	bne fetch_variable_find_addr_next
-
-	iny
-
-#if CONFIG_MEMORY_MODEL_60K
-	jsr peek_under_roms
-#else // CONFIG_MEMORY_MODEL_38K
-	lda (VARPNT),y
-#endif
-
-	cmp VARNAM+1
-
-#endif
-
 	bne fetch_variable_find_addr_next
 
 	// FALLTROUGH

src/basic/engine_variables/fetch_variable_arr.s

@@ -5,6 +5,18 @@
 
 fetch_variable_arr:
 
+	jsr find_array
+	bcc !+
+
+	// Array does not exist - we will have to create one with default parameters
+
+	lda #$00
+	sta VARPNT+1
+!:
+	// Fetch the 'coordinates'
+
 	// XXX implement this
 
+	// XXX finish the implementation
+
 	jmp do_NOT_IMPLEMENTED_error

src/basic/engine_variables/find_array.s

@@ -0,0 +1,89 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+// Carry set = unable to find array
+
+
+find_array:
+
+	 // Initialize VARPNT with the start of array area
+
+	 lda ARYTAB+0
+	 sta VARPNT+0
+	 lda ARYTAB+1
+	 sta VARPNT+1
+
+	 // FALLTROUGH
+
+find_array_loop:
+
+	// Check if end of arrays
+
+	lda VARPNT+1
+	cmp STREND+1
+	bne !+
+	lda VARPNT+0
+	cmp STREND+0
+	bne !+
+
+	// End of arrays
+
+	sec
+	rts
+!:
+	jsr helper_cmp_varnam
+
+#if CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
+	bne_16 find_array_next
+#else // CONFIG_MEMORY_MODEL_38K || CONFIG_MEMORY_MODEL_60K
+	bne find_array_next
+#endif
+
+	// Array found
+
+	clc
+	rts
+
+
+#if CONFIG_MEMORY_MODEL_38K || CONFIG_MEMORY_MODEL_60K
+
+find_array_next:
+
+	// Fetch offset to the next array
+
+	ldy #$03
+
+#if CONFIG_MEMORY_MODEL_60K
+	
+	ldx #<VARPNT
+
+	jsr peek_under_roms
+	pha
+	dey
+	jsr peek_under_roms
+
+#else // CONFIG_MEMORY_MODEL_38K
+
+	lda (VARPNT),y
+	pha
+	dey
+	lda	(VARPNT),y
+
+#endif
+
+	// Adjust VARPNT to point to the next array
+
+	clc
+	adc VARPNT+0
+	sta VARPNT+0
+
+	pla
+	adc VARPNT+1
+	sta VARPNT+1	
+
+	// Next iteration
+
+	bcc find_array_loop                // branch always
+
+#endif

src/basic/engine_variables/find_array_next_46K_50K.s

@@ -0,0 +1,44 @@
+// #LAYOUT# STD *       #TAKE-HIGH
+// #LAYOUT# *   BASIC_0 #TAKE-HIGH
+// #LAYOUT# *   *       #IGNORE
+
+// This has to go $E000 or above - routines below banks out the main BASIC ROM!
+
+
+#if CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
+
+find_array_next:
+
+	// Unmap BASIC lower ROM
+
+	lda #$26
+	sta CPU_R6510
+
+	// Fetch offset to the next array
+
+	ldy #$03
+	lda (VARPNT),y
+	pha
+	dey
+	lda	(VARPNT),y
+
+	// Adjust VARPNT to point to the next array
+
+	clc
+	adc VARPNT+0
+	sta VARPNT+0
+
+	pla
+	adc VARPNT+1
+	sta VARPNT+1	
+
+	// Restore default memory mapping
+
+	lda #$27
+	sta CPU_R6510
+
+	// Next iteration
+
+	jmp find_array_loop
+
+#endif

src/basic/engine_variables/helper_cmp_varnam_38K_60K.s

@@ -0,0 +1,34 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+
+#if CONFIG_MEMORY_MODEL_38K || CONFIG_MEMORY_MODEL_60K
+
+helper_cmp_varnam:
+
+	ldy #$00
+
+#if CONFIG_MEMORY_MODEL_60K
+	ldx #<VARPNT
+	jsr peek_under_roms
+#else // CONFIG_MEMORY_MODEL_38K
+	lda (VARPNT),y
+#endif
+
+	cmp VARNAM+0
+	bne !+
+
+	iny
+
+#if CONFIG_MEMORY_MODEL_60K
+	jsr peek_under_roms
+#else // CONFIG_MEMORY_MODEL_38K
+	lda (VARPNT),y
+#endif
+
+	cmp VARNAM+1
+!:
+	rts
+
+#endif