work towards string deallocation

src/basic/engine/varstr_alloc.s

@@ -19,6 +19,7 @@
 //
 
 // XXX test this routine
+// XXX make it compatible with under-ROM routines
 
 varstr_alloc:
 
@@ -61,15 +62,36 @@ varstr_alloc_retry:
 
 	ldy #$00
 	lda DSCPNT+0
+
+#if CONFIG_MEMORY_MODEL_60K
+	ldx #<FRETOP
+	jsr poke_under_roms
+#else // CONFIG_MEMORY_MODEL_38K || CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
 	sta (FRETOP), y
+#endif
+
 	iny
 	lda DSCPNT+1
+
+#if CONFIG_MEMORY_MODEL_60K
+	jsr poke_under_roms
+#else // CONFIG_MEMORY_MODEL_38K || CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
 	sta (FRETOP), y
+#endif
 
 	// Now lower FRETOP again to make space for the string content
 
 	dey                                          // $01 -> $00
-	lda (DSCPNT), y
+
+#if CONFIG_MEMORY_MODEL_60K
+	ldx #<DSCPNT
+	jsr peek_under_roms
+#elif CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
+	jsr peek_under_roms_via_DSCPNT
+#else // CONFIG_MEMORY_MODEL_38K
+	lda (DSCPNT),y
+#endif
+
 	jsr varstr_FRETOP_down
 	bcs varstr_alloc_fail
 
@@ -77,10 +99,22 @@ varstr_alloc_retry:
 
 	iny                                          // $00 -> $01
 	lda FRETOP+0
-	sta (DSCPNT), y
+
+#if CONFIG_MEMORY_MODEL_60K
+	ldx #<DSCPNT
+	jsr poke_under_roms
+#else // CONFIG_MEMORY_MODEL_38K || CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
+	sta (FRETOP), y
+#endif
+
 	iny
 	lda FRETOP+1
+
+#if CONFIG_MEMORY_MODEL_60K
+	jsr poke_under_roms
+#else // CONFIG_MEMORY_MODEL_38K || CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
 	sta (DSCPNT), y
+#endif
 
 	// The end
 

src/basic/engine/varstr_dealloc.s

@@ -1,9 +0,0 @@
-// #LAYOUT# STD *       #TAKE
-// #LAYOUT# *   BASIC_0 #TAKE
-// #LAYOUT# *   *       #IGNORE
-
-
-varstr_dealloc:
-
-	rts // XXX implement this
-	

src/basic/engine/varstr_free.s

@@ -0,0 +1,75 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+//
+// Releases back memory used by string
+//
+// Input:
+// - DSCPNT+0, DSCPNT+1 - pointer to string descriptor
+//
+
+// XXX test this routine
+
+varstr_free:
+
+	// First copy the string descriptor data to DSCPNT
+	// XXX write optimized version for CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
+
+	ldy #$00
+
+#if CONFIG_MEMORY_MODEL_60K
+	ldx #<DSCPNT
+	jsr peek_under_roms
+#elif CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
+	jsr peek_under_roms_via_DSCPNT
+#else // CONFIG_MEMORY_MODEL_38K
+	lda (DSCPNT),y
+#endif
+
+	sta DSCPNT+2                                 // length of the string
+	iny
+
+#if CONFIG_MEMORY_MODEL_60K
+	jsr peek_under_roms
+#elif CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
+	jsr peek_under_roms_via_DSCPNT
+#else // CONFIG_MEMORY_MODEL_38K
+	lda (DSCPNT),y
+#endif
+
+	pha
+	iny
+
+#if CONFIG_MEMORY_MODEL_60K
+	jsr peek_under_roms
+#elif CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
+	jsr peek_under_roms_via_DSCPNT
+#else // CONFIG_MEMORY_MODEL_38K
+	lda (DSCPNT),y
+#endif
+
+	sta DSCPNT+1
+	pla
+	sta DSCPNT+0
+
+	// Quick check - is the string the lowest one?
+
+	cmp FRETOP+0
+	bne varstr_free_inside
+	lda DSCPNT+1
+	cmp FRETOP+1
+	bne varstr_free_inside
+
+	// This is the lowest string - increase FRETOP, this way
+	// the garbage collector will not be needed that quickly
+
+	// XXX implement this
+
+varstr_free_inside:
+
+	// THis is not the lowest string; mark it as free
+
+	// XXX implement this
+
+	rts

src/basic/memory/under_rom_peek_poke_46k_50k.s

@@ -0,0 +1,89 @@
+// #LAYOUT# STD *       #TAKE-HIGH
+// #LAYOUT# *   BASIC_0 #TAKE-HIGH
+// #LAYOUT# *   *       #IGNORE
+
+// This has to go $E000 or above - as the routines below bank out the main BASIC ROM!
+
+
+#if CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
+
+
+peek_under_roms_via_TXTPTR:
+
+	// Unmap BASIC lower ROM
+
+	lda #$26
+	sta CPU_R6510
+
+	// Retrieve value from under ROMs
+
+	lda (TXTPTR), y
+
+	// FALLTROUGH
+
+peek_under_roms_finalize:
+
+	// Restore memory mapping
+
+	pha
+	lda #$27
+	sta CPU_R6510
+	pla
+
+	// Quit
+
+	rts
+
+peek_under_roms_via_OLDTXT:
+
+	// Unmap BASIC lower ROM
+
+	lda #$26
+	sta CPU_R6510
+
+	// Retrieve value from under ROMs
+
+	lda (OLDTXT), y
+
+#if HAS_OPCODES_65C02
+	bra peek_under_roms_finalize
+#else
+	jmp peek_under_roms_finalize
+#endif
+
+peek_under_roms_via_DSCPNT:
+
+	// Unmap BASIC lower ROM
+
+	lda #$26
+	sta CPU_R6510
+
+	// Retrieve value from under ROMs
+
+	lda (DSCPNT), y
+
+#if HAS_OPCODES_65C02
+	bra peek_under_roms_finalize
+#else
+	jmp peek_under_roms_finalize
+#endif
+
+peek_under_roms_via_FAC1_PLUS_1:
+
+	// Unmap BASIC lower ROM
+
+	lda #$26
+	sta CPU_R6510
+
+	// Retrieve value from under ROMs
+
+	lda (__FAC1 + 1), y
+
+#if HAS_OPCODES_65C02
+	bra peek_under_roms_finalize
+#else
+	jmp peek_under_roms_finalize
+#endif
+
+
+#endif

src/basic/memory/under_rom_shift_46k_50k.s

@@ -8,68 +8,6 @@
 #if CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
 
 
-peek_under_roms_via_TXTPTR:
-
-	// Unmap BASIC lower ROM
-
-	lda #$26
-	sta CPU_R6510
-
-	// Retrieve value from under ROMs
-
-	lda (TXTPTR), y
-
-	// FALLTROUGH
-
-peek_under_roms_finalize:
-
-	// Restore memory mapping
-
-	pha
-	lda #$27
-	sta CPU_R6510
-	pla
-
-	// Quit
-
-	rts
-
-peek_under_roms_via_OLDTXT:
-
-	// Unmap BASIC lower ROM
-
-	lda #$26
-	sta CPU_R6510
-
-	// Retrieve value from under ROMs
-
-	lda (OLDTXT), y
-
-#if HAS_OPCODES_65C02
-	bra peek_under_roms_finalize
-#else
-	jmp peek_under_roms_finalize
-#endif
-
-peek_under_roms_via_FAC1_PLUS_1:
-
-	// Unmap BASIC lower ROM
-
-	lda #$26
-	sta CPU_R6510
-
-	// Retrieve value from under ROMs
-
-	lda (__FAC1 + 1), y
-
-#if HAS_OPCODES_65C02
-	bra peek_under_roms_finalize
-#else
-	jmp peek_under_roms_finalize
-#endif
-
-
-
 shift_mem_up_internal:
 
 	// Move memmove__size bytes from memmove__src to memmove__dst, where memmove__dst > memmove__src