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Assembly Source File | 1990-02-03 | 5.9 KB | 238 lines

; pchcfunc.asm ; ; 11/10/88 by Ted ; ; Low Level RAM functions for Cscape Hercules Graphics support ; ; OWL-PCA 1.2 ; Copyright (c) 1988, 1989 Oakland Group Inc. ; ALL RIGHTS RESERVED ; ; This file contains the low level routines used by display code ; to talk to the Hercules Display Card ; ;------------------------REVISION HISTORY--------------------------------------; ; ;------------------------------------------------------------------------------; include PCDECL.MAC DOS_DATA_PAGE equ 40h ADDR_6845 equ 63h DSEG crtcparms label word db 00h, 35h db 01h, 2Dh db 02h, 2Eh db 03h, 07h db 04h, 5Bh db 05h, 02h db 06h, 57h db 07h, 57h db 09h, 03h CRTCPARMSLEN equ ($-crtcparms)/2 ;--------- BIOSDATAOFFS equ 49h biosdata label byte db 7 ; crt_mode dw 80 ; crt_cols dw 8000h ; crt_len dw 0 ; crt_start dw 8 dup(0) ; cursor_posn dw 0 ; cursor_mode db 0 ; active_page dw 3B4h ; addr_6845 db 0Ah ; crt_mode_set (val for 6845 mode control register) db 0 ; crt_palette (unused) BIOSDATALEN equ $-biosdata ENDDS ;------------------------------------------------------------------------------; retrace_wait macro ;wait for video retrace local L01, L02, L03 ;uses dx for crt port address, trashes al ; leaves interrupts disabled L01: in al, dx ; wait for start of retrace test al, 80h jnz L01 L02: in al, dx ; wait for end of retrace test al, 80h jz L02 cli L03: in al, dx ; wait for start of retrace test al, 80h jnz L03 endm ;------------------------------------------------------------------------------; PSEG ;------------------------------------------------------------------------------; ; boolean herc_present(); ;------------------------ pubproc DIGPRIV herc_present mov dx, 03BAh ; dx = crt status port xor bl, bl ; clear counter in al, dx ; first reading and al, 80h ; clear all but high bit mov ah, al ; save value in ah mov cx, 8000h ; test this many times testchange: in al, dx ; get second reading and al, 80h ; clear all but high bit cmp al, ah ; if no change, keep testing je nochange inc bl ; wait for 25 positives cmp bl, 25 ja gotit ; got 25 positives; quit nochange: loop testchange mov ax, 0 ; didn't get 25 out of 8000h; fail jmp short endtest gotit: mov ax, 1 endtest: ret endproc herc_present ;------------------------------------------------------------------------------; ;/* ; Returns the approximate number of video lines the Herc is currently ; displaying. For herc modes, the possible targets are: ; 7D0h - 80x25 text ; DB6h - 90x39 text ; DC0h - 80x44 text ; F4Bh - 720x348 graphics ;*/ ; int herc_getlines(); ;------------------------ pubproc DIGPRIV herc_getlines ;--------- ; reset light pen latch mov dx, 03BBh ; dx = light pen reset port out dx, al ; clear the latch (al don't care) ; wait for start of next retrace dec dx ; dx = 03BAh (crt status port) retrace_wait ; latch the current crtc address counter in the light pen registers dec dx ; dx = 03B9h (latch load port) out dx, al sti ; return the value in the light pen registers mov dx, 03B4h ; dx = crtc address port mov al, 10h ; al = light pen high register index out dx, al inc dx in al, dx ; read the register mov ah, al dec dx mov al, 11h ; al = light pen low register index out dx, al inc dx in al, dx ; read the register ;--------- ; ax now has the current light pen latch value, i.e. the value of the ; crtc address counter at start of vertical retrace. ret endproc herc_getlines ;------------------------------------------------------------------------------; ; void herc_setgmode(int hpage); ;------------------------ pubproc DIGPRIV herc_setgmode <hpage> push bp mov bp,sp pushm <ds, es, di, si> ;--------- mov bx, 0A01h ; mode control bit for page 0, config switch bit for page 0 mov cl, 6 ; set vidmode 6 for page 0 cmp word ptr [bp].hpage, 0 jz page0 mov bx, 8A03h ; mode control bit for page 1, config switch bit for page 1 mov cl, 5 ; set vidmode 5 for page 1 page0: ; update bios data area mov ax, DOS_DATA_PAGE mov es, ax mov di, BIOSDATAOFFS IF FAR_DATA mov ax, seg DGROUP:biosdata mov ds, ax ENDIF mov si, offset DGROUP:biosdata mov ds:[si], cl ; poke the vidmode: 6 for page 0, 5 for page 1 mov cx, BIOSDATALEN rep movsb ; set configuration switch mov dx, 3BFh ; dx = configuration switch port mov al, bl ; al bit 0 = 1 means enable graphics out dx, al ; al bit 1 = 0 means only use first 32k of video buffer ; blank the screen while programming crtc mov dx, 3B8h ; dx = mode control register xor al, al ; al bit 3 = 0 means disable video signal out dx, al ; blank the screen ; program the crtc sub dl, 4 ; dx = 3B4h = crtc index register mov si, offset DGROUP:crtcparms mov cx, CRTCPARMSLEN putout: lodsw out dx, ax loop putout ; wipe video buffer mov ax, 0B000h cmp word ptr [bp].hpage, 0 jz wpage0 mov ax, 0B800h wpage0: mov es, ax mov ax, 0 mov di, 0 mov cx, 4000h rep stosw ; set graphics mode add dl, 4 ; dx = 3B8h = mode control register mov al, bh ; bit3 = 1 means enable video, bit1 = 1 means graphics mode out dx, al ; bit7 = 1 means page 1 ;--------- popm <si, di, es, ds> pop bp ret endproc herc_setgmode ;------------------------------------------------------------------------------; ; void herc_settmode(); ;------------------------ pubproc DIGPRIV herc_settmode mov ax, 0007h int 10h ; set configuration switch mov dx, 3BFh ; dx = configuration switch port mov al, 0 ; al bit 0 = 0 means disable graphics out dx, al ; al bit 1 = 0 means disable second graphics page ret endproc herc_settmode ;------------------------------------------------------------------------------; ENDPS end ;------------------------------------------------------------------------------;