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[/] [z80soc/] [trunk/] [V0.7.3/] [Software/] [C/] [testsys/] [crt0.s] - Blame information for rev 46

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;; module crt0.s for Z80SoC 0.7.3
;; ==============================
        .module crt0
       .globl   _main
        .area   _HEADER (ABS)
       .org #0
init:
        ;; Stack at the top of memory
        ld      sp,(#0x57D2)
    ;; Initialise global variables
        call    gsinit
        call    _main
        jp      _exit
 
        .area _CODE
        .area _CABS
 
        ;; Ordering of segments for the linker.
        .area   _HOME
        .area   _CODE
        .area   _GSINIT
        .area   _GSFINAL
 
        .area   _DATA
        .area   _BSEG
        .area   _BSS
        .area   _HEAP
 
        .area   _CODE
;       ---------------------------------
; Function putchar
; ---------------------------------
; Z80SoC V0.7.3
_putchar_start::
_putchar::
        push    ix
                        ; get output device port
        ld              a,(#0x57CD)
        or              a
    jr      z,printToVideo
    dec     a
    or      a
    jr      z,printToLCD
    pop     ix
        ret     ; No more valid output peripherals available
 
printToLCD::
    pop     ix
    ret     ; not implemented
 
printToVideo::
        ld              ix,#0
        add             ix,sp
        ld              a,4 (ix)
        cp              #0x0D
        jr              z,ignoreChar
        cp              #0x0A
        ld              hl,(#0x57D0)         ;get video address to print
        jr              z,newLine
        ld              (hl),a                       ;write char to video memory
        inc             hl
    ; these part of the code will get the video coordenates x,y
    ; and calculate the absolute VRAM address to store in 0x57D0
    ; If the cursors has reached the last line, it will not be increased,
    ; that is, cursor will stay pointing to last line.
updtcursorXY::
verifySameLine::
        ld              a,(#0x57CC)         ; get number of columns in video
        ld              b,a
        ld              a,(#0x57CF)         ; get current video X position
        inc             a
        cp              b                               ; compare to current column
        jr              c,sameLine                  ; did not find end of line
newLine::
        ld              a,(#0x57CB)                 ; Number of video lines
        ld              b,a
        ld              a,(#0x57CE)                 ; current video Y position
        inc             a
        cp              b
        jr              c,updtcursorY       ; not end of video screen
        dec             a                   ; end of video screen, keep cursor at last line
updtcursorY::
        ld              (#0x57CE),a                 ; save new video Y position
    ; now need to calcualte absolute vram addres on next line
    ld      a,(#0x57CF)         ;get current X position
    ld      c,a
    xor     a
    ld      b,a
    sbc     hl,bc                ;set vram to start of same line
    ld      a,(#0x57CC)
    ld      c,a
    add     hl,bc                ;next line in the vram
        ;call     _calcVAddress_start
        xor             a
sameLine::
    ld      (#0x57D0),hl
        ld              (#0x57CF),a                 ;save new video X position
ignoreChar::
        pop             ix
        ret
_calcVAddress_start::
_calcVAddress:
;printvars.c:26: return (0x4000 + (readMemory(0x57CC) * y) + 0);
        ld              a,(#0x57CC)                     ; get number of columns in video
        ld              l,a
        ld              h,#0x00
        ld              a,(#0x57CE)                 ; get current video Y
        ld              c,a
        ld              b,#0x00
        call    multiply            ; call multiply routine, return value in hl
        push    hl
    ld      hl,(#0x57D4)        ;get VRAM address
    ld      b,h
    ld      c,l
    pop     hl
        add             hl,bc                       ; calc start of new line
        ld              (#0x57D0),hl        ; store new video address
        ret
_calcVAddress_end::
 
multiply::
        ;; multiply hl * bc and return in hl
        ld              a,b
        or              c                       ; is bc zero ?
        jr              nz,mul0         ; no
        ld              hl,#0x0000      ; X * 0 = zero
        ret
mul0::
        ld              d,h
        ld              e,l
mul::
        dec             bc                      ;dec bc does not update flags
        ld              a,b
        or              c                       ; is bc = zero ?
        ret             z                       ; return HL 
        add             hl,de
        jr              mul
putchar_end::
 
_exit::
        jr              _exit
        .area   _GSINIT
gsinit::
                        ;; outdevice = 0x00 = video
        xor             a
        ld              (#0x57CD),a
        ld              a,#60                  ; screen lines
        ld              (#0x57CB),a
        ld              a,#80                  ; columns
        ld              (#0x57CC),a
        ld              hl,(#0x57D4)           ; get VRAM address
        ld              (#0x57D0),hl           ;current video memory address to print
        xor             a
        ld              (#0x57CE),a             ; video cursor y
        ld              (#0x57CF),a             ; video cursos x
        .area   _GSFINAL
        ret

Line No.	Rev	Author	Line
1	46	rrred	`;; module crt0.s for Z80SoC 0.7.3`
2			`;; ==============================`
3			`.module crt0`
4			`.globl _main`
5			`.area _HEADER (ABS)`
6			`.org #0`
7			`init:`
8			`;; Stack at the top of memory`
9			`ld sp,(#0x57D2)`
10			`;; Initialise global variables`
11			`call gsinit`
12			`call _main`
13			`jp _exit`
14
15			`.area _CODE`
16			`.area _CABS`
17
18			`;; Ordering of segments for the linker.`
19			`.area _HOME`
20			`.area _CODE`
21			`.area _GSINIT`
22			`.area _GSFINAL`
23
24			`.area _DATA`
25			`.area _BSEG`
26			`.area _BSS`
27			`.area _HEAP`
28
29			`.area _CODE`
30			`; ---------------------------------`
31			`; Function putchar`
32			`; ---------------------------------`
33			`; Z80SoC V0.7.3`
34			`_putchar_start::`
35			`_putchar::`
36			`push ix`
37			`; get output device port`
38			`ld a,(#0x57CD)`
39			`or a`
40			`jr z,printToVideo`
41			`dec a`
42			`or a`
43			`jr z,printToLCD`
44			`pop ix`
45			`ret ; No more valid output peripherals available`
46
47			`printToLCD::`
48			`pop ix`
49			`ret ; not implemented`
50
51			`printToVideo::`
52			`ld ix,#0`
53			`add ix,sp`
54			`ld a,4 (ix)`
55			`cp #0x0D`
56			`jr z,ignoreChar`
57			`cp #0x0A`
58			`ld hl,(#0x57D0) ;get video address to print`
59			`jr z,newLine`
60			`ld (hl),a ;write char to video memory`
61			`inc hl`
62			`; these part of the code will get the video coordenates x,y`
63			`; and calculate the absolute VRAM address to store in 0x57D0`
64			`; If the cursors has reached the last line, it will not be increased,`
65			`; that is, cursor will stay pointing to last line.`
66			`updtcursorXY::`
67			`verifySameLine::`
68			`ld a,(#0x57CC) ; get number of columns in video`
69			`ld b,a`
70			`ld a,(#0x57CF) ; get current video X position`
71			`inc a`
72			`cp b ; compare to current column`
73			`jr c,sameLine ; did not find end of line`
74			`newLine::`
75			`ld a,(#0x57CB) ; Number of video lines`
76			`ld b,a`
77			`ld a,(#0x57CE) ; current video Y position`
78			`inc a`
79			`cp b`
80			`jr c,updtcursorY ; not end of video screen`
81			`dec a ; end of video screen, keep cursor at last line`
82			`updtcursorY::`
83			`ld (#0x57CE),a ; save new video Y position`
84			`; now need to calcualte absolute vram addres on next line`
85			`ld a,(#0x57CF) ;get current X position`
86			`ld c,a`
87			`xor a`
88			`ld b,a`
89			`sbc hl,bc ;set vram to start of same line`
90			`ld a,(#0x57CC)`
91			`ld c,a`
92			`add hl,bc ;next line in the vram`
93			`;call _calcVAddress_start`
94			`xor a`
95			`sameLine::`
96			`ld (#0x57D0),hl`
97			`ld (#0x57CF),a ;save new video X position`
98			`ignoreChar::`
99			`pop ix`
100			`ret`
101			`_calcVAddress_start::`
102			`_calcVAddress:`
103			`;printvars.c:26: return (0x4000 + (readMemory(0x57CC) * y) + 0);`
104			`ld a,(#0x57CC) ; get number of columns in video`
105			`ld l,a`
106			`ld h,#0x00`
107			`ld a,(#0x57CE) ; get current video Y`
108			`ld c,a`
109			`ld b,#0x00`
110			`call multiply ; call multiply routine, return value in hl`
111			`push hl`
112			`ld hl,(#0x57D4) ;get VRAM address`
113			`ld b,h`
114			`ld c,l`
115			`pop hl`
116			`add hl,bc ; calc start of new line`
117			`ld (#0x57D0),hl ; store new video address`
118			`ret`
119			`_calcVAddress_end::`
120
121			`multiply::`
122			`;; multiply hl * bc and return in hl`
123			`ld a,b`
124			`or c ; is bc zero ?`
125			`jr nz,mul0 ; no`
126			`ld hl,#0x0000 ; X * 0 = zero`
127			`ret`
128			`mul0::`
129			`ld d,h`
130			`ld e,l`
131			`mul::`
132			`dec bc ;dec bc does not update flags`
133			`ld a,b`
134			`or c ; is bc = zero ?`
135			`ret z ; return HL`
136			`add hl,de`
137			`jr mul`
138			`putchar_end::`
139
140			`_exit::`
141			`jr _exit`
142			`.area _GSINIT`
143			`gsinit::`
144			`;; outdevice = 0x00 = video`
145			`xor a`
146			`ld (#0x57CD),a`
147			`ld a,#60 ; screen lines`
148			`ld (#0x57CB),a`
149			`ld a,#80 ; columns`
150			`ld (#0x57CC),a`
151			`ld hl,(#0x57D4) ; get VRAM address`
152			`ld (#0x57D0),hl ;current video memory address to print`
153			`xor a`
154			`ld (#0x57CE),a ; video cursor y`
155			`ld (#0x57CF),a ; video cursos x`
156			`.area _GSFINAL`
157			`ret`

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Subversion Repositories z80soc

[/] [z80soc/] [trunk/] [V0.7.3/] [Software/] [C/] [testsys/] [crt0.s] - Blame information for rev 46