source: buchla-68k/orig/IOLIB/VPUTCV.S@ c79db87

Last change on this file since c79db87 was 3ae31e9, checked in by Thomas Lopatic <thomas@…>, 8 years ago

Imported original source code.
  • Property mode set to 100755
File size: 2.1 KB
Line 
1* ------------------------------------------------------------------------------
2* vputcv.s -- store a character and attributes in video RAM
3* Version 1 -- 1988-10-05 -- D.N. Lynx Crowe
4* (c) Copyright 1988 -- D.N. Lynx Crowe
5* ------------------------------------------------------------------------------
6*
7* vputcv(adr, row, col, chr, atr, cols)
8* unsigned int *adr, row, col, chr, atr, cols;
9*
10* Stores character 'chr' at ('row', 'col') in the
11* full attribute text object at 'adr' with
12* attribute value 'atr' using a line length of 'len'.
13* ------------------------------------------------------------------------------
14*
15 .text
16*
17 .xdef _vputcv
18*
19P_ADR .equ 8
20P_ROW .equ 12
21P_COL .equ 14
22P_CHR .equ 16
23P_ATR .equ 18
24P_LEN .equ 20
25*
26 .page
27*
28_vputcv: link a6,#0 * Link stack frame pointer
29 move.w P_ROW(a6),d0 * Get row
30 mulu P_LEN(a6),d0 * Multiply by len
31 clr.l d1 * Clear out d1
32 move.w P_COL(a6),d1 * Get col
33 add.l d1,d0 * Add col into d0 to get char. #
34 move.l d0,d1 * Develop cw = (cn/2)*6 in d1
35 andi.l #$FFFFFFFE,d1 * ...
36 move.l d1,d2 * ...
37 add.l d1,d1 * ...
38 add.l d2,d1 * ...
39 add.l P_ADR(a6),d1 * Add sbase to cw
40 movea.l d1,a0 * a0 points at the word with the char.
41 btst.l #0,d0 * Odd char. location ?
42 bne vputcv1 * Jump if so
43*
44 move.w P_CHR(a6),d0 * Get chr
45 andi.w #$00FF,d0 * Mask off garbage bits
46 move.w (a0),d1 * Get word from video RAM
47 andi.w #$FF00,d1 * Mask off old even character
48 or.w d0,d1 * OR in the new character
49 move.w d1,(a0)+ * Store the updated word in video RAM
50 bra vputcvx * Done -- go return to caller
51*
52vputcv1: move.w P_CHR(a6),d0 * Get chr
53 lsl.w #8,d0 * Shift to high (odd) byte
54 move.w (a0),d1 * Get word from video RAM
55 andi.w #$00FF,d1 * Mask off old odd character
56 or.w d0,d1 * OR in the new character
57 move.w d1,(a0)+ * Store the updated word in video RAM
58 addq.l #2,a0 * Point at the attribute word
59*
60vputcvx: move.w P_ATR(a6),(a0) * Store new attributes in video RAM
61 unlk a6 * Unlink the stack frame
62 rts * Return to caller
63*
64 .end
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