more work towards string concatenation, updated binaries and documentation

src/basic/basic_operators/oper_add.s

@@ -52,21 +52,81 @@ oper_add_strings:
 
 	jmp FRMEVL_continue
 !:
-	// Allocate memory for concatenated string
+	// Allocate memory for the concatenated string
 
 	clc
 	adc __FAC2+0
 	bcs_16 do_STRING_TOO_LONG_error
 
-.break
-
 	jsr tmpstr_alloc
 
+	// Copy the temporary string pointer to INDEX
 
+	ldy #$01
+	lda (VARPNT), y
+	sta INDEX+0
+	iny
+	lda (VARPNT), y
+	sta INDEX+1
 
+	// Perform the concatenation
 
-	// XXX finish the implementation
+#if CONFIG_MEMORY_MODEL_60K
+	
+	// XXX
+	// XXX
+	// XXX
 
+#elif CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
+	// XXX consider optimized version without multiple JSRs
+
+	// XXX
+	// XXX
+	// XXX
+
+#else // CONFIG_MEMORY_MODEL_38K
+
+	// Copy data from the first string
+
+	ldy #$00
+!:
+	lda (__FAC2+1),y
+	sta (INDEX),y
+	iny
+	cpy __FAC2+0
+	bne !-
+
+	// Increase INDEX pointer by the size of the 1st string
+
+	tya
+	jsr varstr_INDEX_up_A
+
+	// Copy data from the second string
+
+	ldy #$00
+!:
+	lda (__FAC1+1),y
+	sta (INDEX),y
+	iny
+	cpy __FAC1+0
+	bne !-
+
+#endif
+
+	// Free old strings - if they are temporary
+
+	// XXX
+	// XXX
+	// XXX
+
+	// Copy the descriptor to __FAC1
+
+	ldy #$02
+!:
+	lda (VARPNT), y
+	sta __FAC1, y
+	dey
+	bpl !-
 
 oper_add_strings_end:
 

src/basic/engine/tmpstr_alloc.s

@@ -8,14 +8,38 @@
 // Input:
 // -.A desired string length, has to be > 0
 //
+// Output:
+// - VARPNT points to the newly alocated descriptor
 //
 
 tmpstr_alloc:
 
+	tax
+
 	// First we need to find a free temporary string descriptor
 
-	// XXX TEMPPT-> LASTPT
+	lda TEMPPT
+	cmp #$22
+	bcs_16 do_FORMULA_TOO_COMPLEX_error
 
-	// XXX implement this
+	tay
+	sta LASTPT
+	clc
+	adc #$03
+	sta TEMPPT
 
-	rts
+	// Store desired string length
+
+	stx $00, y
+
+	// Store descriptor address
+
+	lda LASTPT
+	sta VARPNT+0
+	lda #$00
+	sta VARPNT+1
+
+	// Jump to alocation routine
+	// XXX consider falltrough
+
+	jmp varstr_alloc

src/basic/engine/varstr_alloc.s

@@ -20,7 +20,6 @@
 // - fills-in pointer in the string descriptor
 //
 
-// XXX test this routine
 
 varstr_alloc: