From dcbe9d6c5eb0f3f4333c9f368f4cc2d232406cd4 Mon Sep 17 00:00:00 2001
From: FeralChild64 <you@example.com>
Date: Sun, 2 Aug 2020 12:21:50 +0200
Subject: [PATCH] added backpointer rewrite for memory models 46K/50K

---
 src/basic/engine_variables/fetch_variable.s   |  5 --
 .../helper_array_refresh_bptrs.s              | 32 +++++++++---
 ...helper_array_refresh_bptrs_part1_46K_50K.s | 51 +++++++++++++++++++
 ...helper_array_refresh_bptrs_part2_46K_50K.s | 43 ++++++++++++++++
 4 files changed, 120 insertions(+), 11 deletions(-)
 create mode 100644 src/basic/engine_variables/helper_array_refresh_bptrs_part1_46K_50K.s
 create mode 100644 src/basic/engine_variables/helper_array_refresh_bptrs_part2_46K_50K.s

diff --git a/src/basic/engine_variables/fetch_variable.s b/src/basic/engine_variables/fetch_variable.s
index 7678a458..89e40bd1 100644
--- a/src/basic/engine_variables/fetch_variable.s
+++ b/src/basic/engine_variables/fetch_variable.s
@@ -177,11 +177,6 @@ fetch_variable_alocate_adjust_vars:
 
 	// We need to recreate the back-pointers to string arrays
 
-	lda ARYTAB+0
-	sta INDEX+0
-	lda ARYTAB+1
-	sta INDEX+1
-
 	jsr helper_array_refresh_bptrs
 
 	// Fill-in the new variable name and descriptor (it is enough to zero first 2 bytes of content)
diff --git a/src/basic/engine_variables/helper_array_refresh_bptrs.s b/src/basic/engine_variables/helper_array_refresh_bptrs.s
index 3473d866..20882012 100644
--- a/src/basic/engine_variables/helper_array_refresh_bptrs.s
+++ b/src/basic/engine_variables/helper_array_refresh_bptrs.s
@@ -6,9 +6,6 @@
 // Refresh back-pointer to arrays
 //
 
-
-#if CONFIG_MEMORY_MODEL_38K // XXX! create versions for other memory models
-
 helper_array_refresh_bptrs:
 
 	// Refresh back-pointers to arrays
@@ -33,6 +30,17 @@ helper_array_refresh_bptrs_loop_1:
 !:
 	// Calculate start address of the next array, store it in INDEX+2/+3
 
+#if CONFIG_MEMORY_MODEL_60K
+
+	// XXX!
+
+#elif CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
+
+	jsr helper_array_refresh_bptrs_part1
+	bcs helper_array_refresh_bptrs_loop_next
+
+#else // CONFIG_MEMORY_MODEL_38K
+
 	ldy #$02
 
 	lda (INDEX+0), y // XXX
@@ -62,15 +70,27 @@ helper_array_refresh_bptrs_loop_1:
 	adc #$05
 	jsr helper_INDEX_up_A
 
+#endif
+
 	// FALLTROUGH
 
 helper_array_refresh_bptrs_loop_2:
 
 	// Recreate the back-pointer
 
+#if CONFIG_MEMORY_MODEL_60K
+
+	// XXX!
+
+#elif CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
+
+	jsr helper_array_refresh_bptrs_part2
+
+#else // CONFIG_MEMORY_MODEL_38K
+
 	ldy #$00
 	lda (INDEX+0), y // XXX
-	beq helper_array_refresh_bptrs_skip      // skip empty strings
+	beq !+                                       // skip empty strings
 
 	iny
 	clc
@@ -87,6 +107,8 @@ helper_array_refresh_bptrs_loop_2:
 	iny
 	lda INDEX+1
 	sta (INDEX+4), y // XXX
+!:
+#endif
 
 	// FALLTROUGH
 
@@ -118,5 +140,3 @@ helper_array_refresh_bptrs_loop_next:
 helper_array_refresh_bptrs_end:
 
 	rts
-
-#endif
diff --git a/src/basic/engine_variables/helper_array_refresh_bptrs_part1_46K_50K.s b/src/basic/engine_variables/helper_array_refresh_bptrs_part1_46K_50K.s
new file mode 100644
index 00000000..46b7e048
--- /dev/null
+++ b/src/basic/engine_variables/helper_array_refresh_bptrs_part1_46K_50K.s
@@ -0,0 +1,51 @@
+// #LAYOUT# STD *       #TAKE-HIGH
+// #LAYOUT# *   BASIC_0 #TAKE-HIGH
+// #LAYOUT# *   *       #IGNORE
+
+// This has to go $E000 or above - routine below banks out the main BASIC ROM!
+
+#if CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
+
+helper_array_refresh_bptrs_part1:
+
+	// Unmap BASIC lower ROM
+
+	lda #$26
+	sta CPU_R6510
+
+	// Calculate start address of the next array, store it in INDEX+2/+3
+
+	ldy #$02
+
+	lda (INDEX+0), y // XXX
+	clc
+	adc INDEX+0
+	sta INDEX+2 
+	iny
+	lda (INDEX+0), y // XXX
+	adc INDEX+1
+	sta INDEX+3
+
+	// Check if the current array is a string - if not, go to next array
+
+	ldy #$00
+	lda (INDEX+0), y // XXX
+	bmi_16 remap_BASIC_sec_rts
+	iny
+	lda (INDEX+0), y // XXX
+	bpl_16 remap_BASIC_sec_rts
+
+	// It's a string array - scroll INDEX+0/+1 to the first descriptor
+
+	ldy #$04
+	lda (INDEX+0), y // XXX
+	asl
+	clc
+	adc #$05
+	jsr helper_INDEX_up_A
+!:
+	// Restore default memory mapping
+
+	jmp remap_BASIC_clc_rts
+
+#endif
diff --git a/src/basic/engine_variables/helper_array_refresh_bptrs_part2_46K_50K.s b/src/basic/engine_variables/helper_array_refresh_bptrs_part2_46K_50K.s
new file mode 100644
index 00000000..d37c7d4b
--- /dev/null
+++ b/src/basic/engine_variables/helper_array_refresh_bptrs_part2_46K_50K.s
@@ -0,0 +1,43 @@
+// #LAYOUT# STD *       #TAKE-HIGH
+// #LAYOUT# *   BASIC_0 #TAKE-HIGH
+// #LAYOUT# *   *       #IGNORE
+
+// This has to go $E000 or above - routine below banks out the main BASIC ROM!
+
+#if CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
+
+helper_array_refresh_bptrs_part2:
+
+	// Unmap BASIC lower ROM
+
+	lda #$26
+	sta CPU_R6510
+
+	// Write new back-pointer
+
+	ldy #$00
+	lda (INDEX+0), y
+	beq !+
+
+	iny
+	clc
+	adc (INDEX+0), y
+	sta INDEX+4
+	iny
+	lda #$00
+	adc (INDEX+0), y
+	sta INDEX+5
+
+	ldy #$00
+	lda INDEX+0
+	sta (INDEX+4), y
+	iny
+	lda INDEX+1
+	sta (INDEX+4), y
+
+!:
+	// Restore default memory mapping
+
+	jmp remap_BASIC
+
+#endif