some preparations for string variables, added BASIC command COLD

2020-07-02 17:24:34 +02:00
1 parent 34b56b1fd5
commit 164d090a43
@@ -32,6 +32,7 @@
 .label panic               = KERNAL().panic
 #endif

+.label vector_reset        = KERNAL().vector_reset
 .label hw_entry_reset      = KERNAL().hw_entry_reset

 #if CONFIG_DBG_PRINTF
@@ -15,7 +15,8 @@
 	cmd_bsave,
 	cmd_bverify,

-	cmd_old
+	cmd_old,
+	cmd_cold
 )


@@ -0,0 +1,12 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+
+cmd_cold:
+
+	jsr helper_ask_if_sure
+	bcs_16 execute_statements
+
+	jsr JCLALL                         // for extra safety
+	jmp (vector_reset)                 // hardware CPU vector
@@ -0,0 +1,65 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+//
+// For direct mode, asks the user if he is sure (sets Carry if not);
+// otherwise returns with Carry clear
+//
+
+
+helper_ask_if_sure:
+
+	// First check, if we are in direct mode,; if not, do not ask
+
+	ldx CURLIN+1
+	inx
+	bne helper_ask_if_sure_ok                    // branch if not direct mode
+
+	// Not direct mode - display the question
+
+	ldx #IDX__STR_IF_SURE
+	jsr print_packed_misc_str
+
+	// Clear the keyboard queue
+
+	lda #$00
+	sta NDX
+
+	// Enable cursor, fetch the answer
+
+	lda #$00
+	sta BLNSW
+!:
+	jsr JGETIN
+	cmp #$00
+	beq !-
+
+	// Check if 'Y'
+
+	cmp #$59
+	beq !+
+
+	lda #$4E                                     // 'N'
+	jsr JCHROUT
+
+	sec
+	rts
+!:
+	// Display 'Y' and wait a short moment for a better user experience
+
+	jsr JCHROUT
+
+	clc
+	lda TIME+0
+	adc #$0C
+!:
+	cmp TIME+0
+	bne !-
+
+	// FALLTROUGH
+
+helper_ask_if_sure_ok:
+
+	clc
+	rts
@@ -58,7 +58,7 @@ oper_add_strings:
 	adc __FAC2+0
 	bcs_16 do_STRING_TOO_LONG_error

-	jsr alloc_temp_string
+	// jsr alloc_temp_string

 .break

@@ -9,6 +9,11 @@ shell_main_loop:
 	ldx #IDX__STR_READY
 	jsr print_packed_misc_str

+	// Mark mode as direct
+
+	lda #$FF
+	sta CURLIN+1
+
 	// Enable Kernal messages
 	lda #$80
 	jsr JSETMSG
@@ -1,26 +0,0 @@
-// #LAYOUT# STD *       #TAKE
-// #LAYOUT# *   BASIC_0 #TAKE
-// #LAYOUT# *   *       #IGNORE
-
-//
-// Allocates area for a temporary string
-//
-// Input:
-// - .A - string length
-//
-
-
-// XXX - finish the implementation once string memory handling is done
-
-
-alloc_temp_string:
-
-	// Check if temporary descriptor stack has a free slot
-
-	ldx LASTPT
-	cpx #$1F
-	bcs_16 do_FORMULA_TOO_COMPLEX_error
-
-	// XXX
-
-	jmp do_NOT_IMPLEMENTED_error
@@ -0,0 +1,106 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+//
+// Allocates memory for string - lowers FRETOP (but not below STREND)
+//
+// Note: We are not going to use the C64-style memory management here, as it implies
+// a very slow garbage collector. Instead, we are using a scheme similar to used in
+// BASIC V3.5 and later, with 'back-pointers' after each string, telling about the
+// location of the string descriptor. 
+//
+// See:
+// - https://www.c64-wiki.com/wiki/Memory_(BASIC)
+// - https://sites.google.com/site/h2obsession/CBM/basic/variable-format
+//
+// Input:
+// - DSCPNT+0, DSCPNT+1 - pointer to string descriptor, first pointed byte should contain desired length
+//
+
+varstr_alloc:
+
+	// Mark garbage collector as not run yet
+
+	lda #$00
+
+	// FALLTROUGH
+
+varstr_alloc_retry:
+
+	sta GARBFL                                   // Computes Mapping the Commodore 64, page 10
+
+	// Backup FRETOP in case of alocation problems
+
+	lda FRETOP+0
+	sta INDEX+0
+	lda FRETOP+1
+	sta INDEX+1
+
+	// Lower FRETOP to make space for string descriptor
+
+#if !HAS_OPCODES_65CE02
+
+	lda #$02
+	jsr varstr_FRETOP_down 
+
+#else // HAS_OPCODES_65CE02
+
+	dew FRETOP
+	dew FRETOP
+
+#endif
+
+	jsr varstr_FRETOP_check
+	bcs varstr_alloc_fail
+
+	// XXX finish this
+
+
+
+
+
+varstr_alloc_fail:
+
+	// Unable to alocate memory - restore FRETOP value
+
+	lda INDEX+0
+	sta FRETOP+0
+	lda INDEX+1
+	sta FRETOP+1
+
+	// Check if it is worth to perform garbage collection and retry
+
+	bit GARBFL
+
+	// XXX finish this
+
+
+
+
+// XXX move these helper routines to a better place
+
+
+varstr_FRETOP_down: // memmove__tmp - length to lower FRETOP
+
+	sec
+	lda FRETOP+0
+	sbc memmove__tmp
+	sta FRETOP+0
+	bcs !+
+	dec FRETOP+1
+!:
+	rts
+
+varstr_FRETOP_check:
+
+	// Check if FRETOP > STREND, Carry set if not
+
+	lda STREND+1
+	cmp FRETOP+1
+	beq !+
+	rts
+!:
+	lda STREND+0
+	cmp FRETOP+0
+	rts
@@ -0,0 +1,9 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+
+varstr_dealloc:
+
+	rts // XXX implement this
+	
@@ -0,0 +1,8 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+
+varstr_garbage_collect:
+
+	rts // XXX implement this
@@ -9,13 +9,13 @@

 shift_mem_adapt_pointers:

-	sty RESHO+4
+	sty memmove__tmp

 	// Adapt source pointer

 	sec
 	lda memmove__src+0
-	sbc RESHO+4
+	sbc memmove__tmp
 	sta memmove__src+0
 	bcs !+
 	dec memmove__src+1
@@ -24,7 +24,7 @@ shift_mem_adapt_pointers:

 	sec
 	lda memmove__dst+0
-	sbc RESHO+4
+	sbc memmove__tmp
 	sta memmove__dst+0
 	bcs !+
 	dec memmove__dst+1
@@ -0,0 +1,9 @@
+
+//
+// Aliases for memory locations for memory block copy routines
+//
+
+.label memmove__src    = INDEX+2
+.label memmove__dst    = RESHO+0
+.label memmove__size   = RESHO+2
+.label memmove__tmp    = RESHO+4
@@ -11,7 +11,7 @@
 // - memmove__dst  - pointer to the first byte of destination
 // - memmove__size - number of bytes to copy
 //
-// All the input variables, .A, and .Y register, are destroyed. Also uses RESHO+4 variable.
+// All the input variables, .A, and .Y register, are destroyed. Also uses memmove__tmp variable.
 //


@@ -11,7 +11,7 @@
 // - memmove__dst  - pointer to the last byte of destination
 // - memmove__size - number of bytes to copy
 //
-// All the input variables, .A, and .Y register, are destroyed. Also uses RESHO+4 variable.
+// All the input variables, .A, and .Y register, are destroyed. Also uses memmove__tmp variable.
 //