From cabcfb6b358d2bdddc978be060219305f29f5641 Mon Sep 17 00:00:00 2001
From: FeralChild64 <you@example.com>
Date: Thu, 16 Jul 2020 19:06:40 +0200
Subject: [PATCH] fixed comparing uninitialized streing descriptor

---
 src/basic/basic_commands/cmd_let.s            | 50 +++++++++++++++----
 .../helper_let_strdesccpy_46K_50K.s           | 40 +++++++++++++++
 2 files changed, 80 insertions(+), 10 deletions(-)
 create mode 100644 src/basic/basic_commands/helper_let_strdesccpy_46K_50K.s

diff --git a/src/basic/basic_commands/cmd_let.s b/src/basic/basic_commands/cmd_let.s
index 9a81e8a0..580b4221 100644
--- a/src/basic/basic_commands/cmd_let.s
+++ b/src/basic/basic_commands/cmd_let.s
@@ -11,16 +11,20 @@ cmd_let:
 	jsr fetch_variable
 
 #if HAS_OPCODES_65CE02
+
 	bcs_16 do_SYNTAX_error
 	jsr injest_assign
 	bcs_16 do_SYNTAX_error
+
 #else
+
 	bcs !+
 	jsr injest_assign
 	bcc !++
 !:
 	jmp do_SYNTAX_error
 !:
+
 #endif
 
 	// Determine variable type and push it to the stack
@@ -132,16 +136,21 @@ cmd_let_assign_string:
 
 #if CONFIG_MEMORY_MODEL_60K
 	
-	// XXX
-	// XXX: implement this
-	// XXX
+	ldx #<VARPNT
+
+	ldy #$00
+	jsr peek_under_roms
+	sta DSCPNT+0
+	iny
+	jsr peek_under_roms
+	sta DSCPNT+1
+	iny
+	jsr peek_under_roms
+	sta DSCPNT+2
 
 #elif CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
-	// XXX consider optimized version without multiple JSRs
 
-	// XXX
-	// XXX: implement this
-	// XXX
+	jsr helper_let_strdesccpy
 
 #else // CONFIG_MEMORY_MODEL_38K
 
@@ -269,10 +278,14 @@ cmd_let_assign_string_not_text_area:
 	ldy #$00
 
 #if CONFIG_MEMORY_MODEL_60K
+
 	ldx #<VARPNT
 	jsr poke_under_roms
+
 #else // CONFIG_MEMORY_MODEL_38K || CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
+	
 	sta (VARPNT), y
+
 #endif
 
 	lda __FAC1+0
@@ -284,9 +297,26 @@ cmd_let_assign_string_not_text_area:
 
 #if CONFIG_MEMORY_MODEL_60K
 	
-	// XXX
-	// XXX: implement this
-	// XXX
+	ldx #<VARPNT
+
+	ldy #$02
+	jsr peek_under_roms
+	sta DSCPNT+2
+	dey
+	jsr peek_under_roms
+	sta DSCPNT+1
+	dey
+
+	// .Y is now 0 - copy the content
+!:
+
+	ldx #<__FAC1+1
+	jsr peek_under_roms
+	ldx #<DSCPNT+1
+	jsr poke_under_roms
+	iny
+	cpy __FAC1+0
+	bne !-
 
 #elif CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
 	
diff --git a/src/basic/basic_commands/helper_let_strdesccpy_46K_50K.s b/src/basic/basic_commands/helper_let_strdesccpy_46K_50K.s
new file mode 100644
index 00000000..b0b18ea6
--- /dev/null
+++ b/src/basic/basic_commands/helper_let_strdesccpy_46K_50K.s
@@ -0,0 +1,40 @@
+// #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!
+
+//
+// Helper routine to copy string descriptor, for LET command
+//
+
+
+#if CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
+
+helper_let_strdesccpy:
+
+	// Unmap BASIC lower ROM
+
+	lda #$26
+	sta CPU_R6510
+
+	// Retrieve pointer to destination
+
+	ldy #$00
+	lda (VARPNT), y
+	sta DSCPNT+0
+	iny
+	lda (VARPNT), y
+	sta DSCPNT+1
+	iny
+	lda (VARPNT), y
+	sta DSCPNT+2
+
+	// Restore default memory mapping
+
+	lda #$27
+	sta CPU_R6510
+
+	rts
+
+#endif