Adding Browse interface. Max lines limited to 255 which causes unintended wrap around on display.

afscanner.s

@@ -300,6 +300,8 @@ SetScreen
 		da  AboutInit, AboutDisplay, AboutKeypress
 		dfb "F"
 		da  FieldInit, FieldDisplay, FieldKeypress
+		dfb "B"
+		da	BrowseInit, BrowseDisplay, BrowseKeypress
 		dfb 0	; end
 
 *
@@ -359,6 +361,7 @@ AboutInit		; Returns with Acc = max lines
 		asc _INVERSE,_MT_ON,_O_APPLE,_MT_OFF,_NORMAL,"A = This about page.",$00
 		asc _INVERSE,_MT_ON,_O_APPLE,_MT_OFF,_NORMAL,"F = Address field display.  " ; (cont)
 		asc "(Assuming 'good' address fields on disk.)",$00
+		asc _INVERSE,_MT_ON,_O_APPLE,_MT_OFF,_NORMAL,"B = Browse track buffer.",$00
 		asc " ",$00
 		asc "Source available at https://github.com/a2geek/afscanner",$00
 		asc " ",$00
@@ -388,6 +391,21 @@ AboutInit		; Returns with Acc = max lines
 		da  PROLOGUE+2
 		dfb $00
 		asc " ",$00
+		asc "Browse Track Buffer",$00
+		asc "===================",$00
+		asc " ",$00
+		asc "Browse the raw track buffer.  Header fields are hilighted.  Note that the ",$00
+		asc "buffer is $2000 (8192) bytes long and some sectors will be repeated.",$00
+		asc " ",$00
+		asc "Headers are currently set to "
+		dfb 1
+		da  PROLOGUE
+		dfb " ",1
+		da  PROLOGUE+1
+		dfb " ",1
+		da  PROLOGUE+2
+		dfb $00
+		asc " ",$00
 		asc "-END-",$00
 		dfb 0
 
@@ -537,6 +555,98 @@ FieldKeypress		; Called with Acc = key
 		bcs :setup
 		bcc :setdst
 
+*		
+* BROWSE interface
+*
+
+BrowseInit			; Returns with Acc = max lines
+		jsr PRINT
+		asc _INVERSE,_MT_ON,_U_ARROW,_D_ARROW,_MT_OFF,_NORMAL," Scroll / "
+		asc _INVERSE,_MT_ON,_O_APPLE,_NORMAL,"-",_INVERSE,_U_ARROW,_D_ARROW,_MT_OFF,_NORMAL," Page / "
+		asc _MT_ON,_INVERSE,_L_ARROW,_R_ARROW,_NORMAL,_MT_OFF," Track / "
+		asc "re",_INVERSE,"S",_NORMAL,"can / "
+		asc _INVERSE,"R",_NORMAL,"ecalibrate / "
+		asc "goto ",_INVERSE,"T",_NORMAL,"rack"
+		dfb 0
+
+* Scan for our prologue mark them by turning off the high bit
+
+		jsr ReadTrack		; position head and fully populate buffer
+		jsr SETUPDATA
+:scan	ldy #0				; index for comparisons
+:loop	lda (DATA),y
+		cmp PROLOGUE,Y
+		bne :adv
+		iny
+		cpy #3
+		bcc :loop
+; We found prologue bytes, strip off high bit
+:strip	dey
+		bmi :adv
+		lda (DATA),y
+		and #$7f
+		sta (DATA),y
+		bne :strip		; should be always
+:adv	inc DATA
+		bne :scan
+		inc DATA+1
+		dec TEMP
+		bne :scan
+; The number of lines is based on how many bytes we show on screen
+; HOWEVER, we are limited to 255 lines, so we actually skip the last 32 bytes
+		lda #$ff
+		rts
+
+BrowseDisplay		; Called with Acc = line
+; Calculate buffer address
+		sta DATA
+		stz DATA+1
+		ldy #5		; times 32
+:mult32	asl DATA
+		rol DATA+1
+		dey
+		bne :mult32
+		clc
+		lda #>DATASTART
+		adc DATA+1
+		sta DATA+1
+; Display offset
+		lda #"+"
+		jsr COUT
+		lda DATA+1
+		and #$3f
+		jsr PRHEX
+		lda DATA
+		jsr PRHEX
+		jsr PRINT
+		asc "-  ",$00
+; Display 'disk' bytes, highlighting the field markers (high bit was stripped off in init routine)
+		ldy #0
+:nxtbyt	lda (DATA),y
+		bmi :prhex
+		pha
+		lda #_INVERSE
+		jsr COUT
+		pla
+		ora #$80
+:prhex	jsr PRHEX
+		lda #_NORMAL
+		jsr COUT
+		tya
+		and #$07
+		cmp #$07
+		bne :testy
+		lda #" "
+		jsr COUT
+:testy	iny
+		cpy #32
+		bne :nxtbyt
+		jmp PRCR
+
+BrowseKeypress		; Called with Acc = key
+		jmp FieldKeypress	; identical to Field ... for now at least
+
+
 *
 * DISK II routines
 *