Merge pull request #148 from smuehlst/c1p

kbhit() implementation, fixed C data stack pointer initialization

cfg/osic1p.cfg

@@ -7,7 +7,7 @@ SYMBOLS {
 }
 MEMORY {
     # for size of ZP see runtime/zeropage.s and c1p/extzp.s
-    ZP:       file = "", define = yes, start = $0002, size = $001A + $0004;
+    ZP:       file = "", define = yes, start = $0002, size = $001A + $0005;
     RAM:      file = %O, define = yes, start = %S, size = __HIMEM__ - __STACKSIZE__ - %S;
 }
 SEGMENTS {

doc/osi.sgml

@@ -137,10 +137,6 @@ There are no loadable drivers available.
 
 <sect>Limitations<p>
 
-<sect1>conio implementation<p>
-
-The conio implementation is complete except for a kbhit() function. 
-
 <sect1>stdio implementation<p>
 
 There is no support for stdio at the moment.

libsrc/osic1p/_scrsize.s

@@ -13,7 +13,7 @@
         .include        "osic1p.inc"
 
 .proc   screensize
-        ldx     #(SCR_LINELEN + 1)
+        ldx     #SCR_WIDTH
-        ldy     #(SCR_HEIGHT + 1)
+        ldy     #SCR_HEIGHT
         rts
 .endproc

libsrc/osic1p/cclear.s

@@ -22,7 +22,7 @@ _cclear:
         cmp     #0              ; Is the length zero?
         beq     L9              ; Jump if done
         sta     tmp1                                 
-L1:     lda     #$20            ; Blank - screen code
+L1:     lda     #' '
         jsr     cputdirect      ; Direct output
         dec     tmp1
         bne     L1

libsrc/osic1p/cgetc.s

@@ -1,6 +1,8 @@
 ;
 ; char cgetc (void);
 ;
+
+        .constructor    initcgetc
         .export         _cgetc
         .import         cursor
 
@@ -8,8 +10,21 @@
         .include        "extzp.inc"
         .include        "zeropage.inc"
 
+; Initialize one-character buffer that is filled by kbhit()
+initcgetc:
+        lda     #$00
+        sta     CHARBUF         ; No character in buffer initially
+        rts
+
 ; Input routine from 65V PROM MONITOR, show cursor if enabled
 _cgetc:
+        lda     CHARBUF         ; character in buffer available?
+        beq     nobuffer
+        tax                     ; save character in X
+        lda     #$00
+        sta     CHARBUF         ; empty buffer
+        beq     restorex        ; restore X and return
+nobuffer:
         lda     cursor          ; show cursor?
         beq     nocursor
         ldy     CURS_X
@@ -25,7 +40,9 @@ nocursor:
         lda     tmp1            ; fetch saved character
         ldy     CURS_X
         sta     (SCREEN_PTR),y  ; store at cursor position
+
+restorex:
         txa                     ; restore saved character from X
-        ldx     #$00            ; high byte of int return value
 done:
+        ldx     #$00            ; high byte of int return value
         rts

libsrc/osic1p/clrscr.s

@@ -12,7 +12,7 @@
 BANKS = VIDEORAMSIZE / $100
 
 _clrscr:
-        lda       #$20          ; ' '
+        lda       #' '
         ldy       #BANKS
         ldx       #$00
 staloc:

libsrc/osic1p/cputc.s

@@ -12,6 +12,10 @@
         .include        "osic1p.inc"
         .include        "extzp.inc"
 
+FIRSTVISC       = $85           ; Offset of first visible character in video RAM
+LINEDIST        = $20           ; Offset in video RAM between two lines
+BLOCKSIZE       = $100          ; Size of block to scroll
+
 _cputcxy:
         pha                     ; Save C
         jsr     popa            ; Get Y
@@ -35,9 +39,9 @@ cputdirect:
 ; Advance cursor position
 
 advance:
-        cpy     #SCR_LINELEN    ; xsize-1
+        cpy     #(SCR_WIDTH - 1)
         bne     L3
-        jsr     newline         ; new line
+        jsr     newline         ; New line
         ldy     #$FF            ; + cr
 L3:     iny
         sty     CURS_X
@@ -46,10 +50,25 @@ L3:     iny
 newline:
         inc     CURS_Y
         lda     CURS_Y
-        cmp     #SCR_HEIGHT     ; screen height
+        cmp     #SCR_HEIGHT     ; Screen height
         bne     plot
-        lda     #0              ; wrap around to line 0
+        dec     CURS_Y          ; Bottom of screen reached, scroll
-        sta     CURS_Y
+        ldx     #0
+scroll:
+.repeat 3, I                    ; Scroll screen in three blocks of size
+                                ; BLOCKSIZE
+        lda     SCRNBASE+(I*BLOCKSIZE)+FIRSTVISC+LINEDIST,x
+        sta     SCRNBASE+(I*BLOCKSIZE)+FIRSTVISC,x
+.endrepeat
+        inx
+        bne scroll
+
+        lda     #' '            ; Clear bottom line of screen
+bottom:
+        sta     SCRNBASE+(3*BLOCKSIZE)+FIRSTVISC,x
+        inx
+        cpx     #SCR_WIDTH
+        bne     bottom
 
 plot:   ldy     CURS_Y
         lda     ScrLo,y

libsrc/osic1p/crt0.s

@@ -9,6 +9,7 @@
 
 .export   __STARTUP__ : absolute = 1    ; Mark as startup
 .import   __RAM_START__, __RAM_SIZE__   ; Linker generated
+.import   __STACKSIZE__
 
 .import    zerobss, initlib, donelib
 
@@ -31,9 +32,9 @@ _init:    ldx     #$FF          ; Initialize stack pointer to $01FF
 ; ---------------------------------------------------------------------------
 ; Set cc65 argument stack pointer
 
-          lda     #<(__RAM_START__ + __RAM_SIZE__)
+          lda     #<(__RAM_START__ + __RAM_SIZE__  + __STACKSIZE__)
           sta     sp
-          lda     #>(__RAM_START__ + __RAM_SIZE__)
+          lda     #>(__RAM_START__ + __RAM_SIZE__  + __STACKSIZE__)
           sta     sp+1
 
 ; ---------------------------------------------------------------------------

libsrc/osic1p/extzp.inc

@@ -4,4 +4,4 @@
 
 ; ------------------------------------------------------------------------
 
-        .globalzp       CURS_X, CURS_Y, SCREEN_PTR
+        .globalzp       CURS_X, CURS_Y, SCREEN_PTR, CHARBUF

libsrc/osic1p/extzp.s

@@ -14,6 +14,7 @@
 CURS_X:         .res    1
 CURS_Y:         .res    1
 SCREEN_PTR:     .res    2
+CHARBUF:        .res    1
 
-; size 4
+; size 5
-; Adjust size of this segment in osic1p.cfg if the size changes
+; Adjust size of the ZP segment in osic1p.cfg if the size changes

libsrc/osic1p/kbhit.s

@@ -0,0 +1,47 @@
+;
+; unsigned char kbhit (void);
+;
+; The method to detect a pressed key is based on the documentation in
+; "Section 3 Programmed Key Functions" in "The Challenger Character Graphics
+; Reference Manual"
+; We only want to return true for characters that can be returned by cgetc(),
+; but not for keys like <Shift> or <Ctrl>. Therefore a special handling is
+; needed for the first row. This is implemented by a bit mask that is stored
+; in tmp1 and that is set to zero after the first round.
+;
+
+        .export _kbhit
+        .include "osic1p.inc"
+        .include "extzp.inc"
+        .include "zeropage.inc"
+
+_kbhit:
+        lda     #%11011111      ; Mask for only checking the column for the
+        sta     tmp1            ; ESC key in the first keyboard row.
+
+        lda     #%11111110      ; Mask for first keyboard row
+scan:
+        sta     KBD             ; Select keyboard row
+        tax                     ; Save A
+        lda     KBD             ; Read keyboard columns
+        ora     tmp1            ; Mask out uninteresting keys (only relevant in
+                                ; first row)
+        cmp     #$FF            ; No keys pressed?
+        bne     keypressed
+        lda     #$00            ; For remaining rows no keys masked
+        sta     tmp1
+        txa                     ; Restore A
+        sec                     ; Want to shift in ones
+        rol     a               ; Rotate row select to next bit position
+        cmp     #$FF            ; Done?
+        bne     scan            ; If not, continue
+        lda     #$00            ; Return false
+        tax                     ; High byte of return is also zero
+        sta     CHARBUF         ; No character in buffer
+        rts
+keypressed:
+        jsr     INPUTC          ; Get input character in A
+        sta     CHARBUF         ; Save in buffer
+        ldx     #$00            ; High byte of return is always zero
+        lda     #$01            ; Return true
+        rts

libsrc/osic1p/osic1p.inc

@@ -2,8 +2,9 @@
 SCRNBASE        := $D000        ; Base of video RAM
 INPUTC          := $FD00        ; Input character from keyboard
 RESET           := $FF00        ; Reset address, show boot prompt
+KBD             := $DF00        ; Polled keyboard register
 
 ; Other definitions
 VIDEORAMSIZE    = $0400         ; Size of C1P video RAM (1 kB)
-SCR_LINELEN     = $18           ; screen width - 1
+SCR_WIDTH       = $18           ; Screen width
-SCR_HEIGHT      = $18           ; screen height - 1
+SCR_HEIGHT      = $18           ; Screen height