more work towards string concatenation, updated binaries and documentation

README.md

@@ -6,11 +6,13 @@ A project to create unencumbered open-source ROMs for use on selected retro comp
 
 * [implementation status](./STATUS.md) of various APIs and functionalities
 * [configuration options](./CONFIG.md) for those willing to compile their own, customized ROM set
-* [BASIC extensions](doc/Extended-BASIC.md)
+* [BASIC extensions](./doc/Extended-BASIC.md)
 * [development guide](./doc/Development.md) for those interested in technical aspects
 * [license](./LICENSE) information and list of major contributors
 * [credits](./CREDITS.md) to people whose work was of great help to us
 
+To download pre-built ROM images, go [here](./bin).
+
 # Problem Statement and Motivation
 
 The copyrights of various old computer system ROMs are still alive, and together with trademarks, can present significant

STATUS.md

@@ -11,6 +11,12 @@ Here are the features of the Open ROMs not found in the original ROMs from the 8
 * JiffyDOS and DolphinDOS protocols support
 * DOS wedge (direct mode only) - `@<drive_number>`, `@<command>`, `@$`, `@$<params>`, `@`
 * BASIC extensions, see the [documentation](doc/Extended-BASIC.md) 
+* extended / tweaked `LOAD` / `VERIFY` commands
+    * start/end addresses are displayed, in the Final cartridge style
+    * command with just the file name tries to use the last device if it's number seems sane; otherwise uses 8
+    * command without parameters tries to load first file from drive chosen as above
+* `LIST` command should never damage the screen if trying to list memory content which is not a BASIC program
+* high performance garbage collector
 
 * turbo tape load support (as device 7, or using `←L` / `←M`, optionally with a file name), quite sophisticated: up to 250 blocks (can store bytes under I/O), automatically adjusts for tape speed differences
 * normal tape load error log is limited by free stack space only (no artificial limitation like in original ROMs)
@@ -18,12 +24,6 @@ Here are the features of the Open ROMs not found in the original ROMs from the 8
 * improved support for tape adapters (for using regular casette players and other audio devices instead of Datasette) and emulators
 * built-in tape head align tool (only feasible to use on machines with extended memory, like Mega65)
 
-* extended / tweaked `LOAD` / `VERIFY` commands
-    * start/end addresses are displayed, in the Final cartridge style
-    * command with just the file name tries to use the last device if it's number seems sane; otherwise uses 8
-    * command without parameters tries to load first file from drive chosen as above
-* `LIST` command should never damage the screen if trying to list memory content which is not a BASIC program
-
 * uses RAM under ROM and I/O: 51199 bytes free (up to `$CFFF`) by default, but 61438 is also possible
 * cold/warm start silences multiple SID chips
 * warm start due to BRK prints out the instruction address
@@ -42,7 +42,7 @@ The following ROM features are currently missing and are not planned due to spac
 The following ROM features are currently missing:
 
 * most BASIC commands
-* BASIC variables
+* BASIC variables (work in progress, strings partially work now)
 * BASIC expression handling
 * most floating point routines
 * RS-232 support

src/,,config_custom.s

@@ -39,9 +39,9 @@
 
 // Memory model
 
-// #define CONFIG_MEMORY_MODEL_38K
+#define CONFIG_MEMORY_MODEL_38K
 // #define CONFIG_MEMORY_MODEL_46K
-#define CONFIG_MEMORY_MODEL_50K
+// #define CONFIG_MEMORY_MODEL_50K
 // #define CONFIG_MEMORY_MODEL_60K
 
 

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: