source: buchla-68k/vlib/acctrl.s@ cc2c9e0

Last change on this file since cc2c9e0 was 4f508e6, checked in by Thomas Lopatic <thomas@…>, 7 years ago

Converted assembly language files.
  • Property mode set to 100644
File size: 4.1 KB
Line 
1| ------------------------------------------------------------------------------
2| acctrl.s -- VSDD access table control functions
3| Version 6 -- 1987-04-13 -- D.N. Lynx Crowe
4| (c) Copyright 1987 -- D.N. Lynx Crowe
5| ------------------------------------------------------------------------------
6
7| objclr(obj)
8| unsigned int obj;
9
10| Clear bits in access table for object 'obj'.
11| Disables object 'obj'.
12
13| objoff(obj, line, num)
14| unsigned int obj, line, num;
15
16| Disable object obj at line thru line+num.
17
18| objon(obj, line, num)
19| unsigned int obj, line, num;
20
21| Enable object obj at line thru line+num.
22
23
24| Assumes VSDD is looking at bank 0.
25| Assumes a screen height of 350 lines.
26| No error checks are done, so beware.
27| ------------------------------------------------------------------------------
28 .text
29
30 .xdef _objclr,_objoff,_objon
31
32 .xref _v_actab
33
34SCSIZE = 350 | Screen height
35
36OBJ = 8 | Object number argument offset
37LINE = 10 | Beginning line argument offset
38NUM = 12 | Object height argument offset
39| ------------------------------------------------------------------------------
40 .page
41| ------------------------------------------------------------------------------
42
43| objclr(obj)
44| unsigned int obj;
45
46| Disables object obj in access table by turning on
47| its bit in all words of the access table.
48| ------------------------------------------------------------------------------
49_objclr: link a6,#0 | Link stack frames
50 move.w OBJ(a6),d1 | Get object bit number in d1
51 lea _v_actab,a0 | Get base of object table in a0
52 move.w #SCSIZE-1,d2 | Put line count in d2
53
54objclr1: move.w (a0),d0 | Get access table word
55 bset.l d1,d0 | Set the bit
56 move.w d0,(a0)+ | Update word in access table
57 dbf d2,objclr1 | Loop until done
58
59 unlk a6 | Unlink stack frame
60 rts | Return to caller
61
62 .page
63| ------------------------------------------------------------------------------
64| objoff(obj, line, num)
65| unsigned int obj, line, num;
66
67| Turn on access table bits for object 'obj' at
68| lines 'line' through 'line'+'num'. Disables the object.
69| Assumes object bits were set at those locations.
70| ------------------------------------------------------------------------------
71_objoff: link a6,#0 | Link stack frames
72 move.w OBJ(a6),d1 | Get object bit number into d1
73 move.w LINE(a6),d2 | Get top line number
74 add.w d2,d2 | Convert to word offset
75 lea _v_actab,a0 | Get base address of access table
76 move.w 0(a0,d2),d0 | Get top line access word
77 bset.l d1,d0 | Set object bit
78 move.w d0,0(a0,d2) | Update word in access table
79 tst.w NUM(a6) | Number of lines = 0 ?
80 beq objoff1 | Done if so
81
82 move.w NUM(a6),d2 | Get object depth
83 add.w LINE(a6),d2 | Add to top line number
84 cmpi.w #SCSIZE,d2 | Bottom line >= screen height ?
85 bge objoff1 | Done if so
86
87 add.w d2,d2 | Convert to word offset
88 move.w 0(a0,d2),d0 | Get bottom line access word
89 bset.l d1,d0 | Set object bit
90 move.w d0,0(a0,d2) | Update word in access table
91
92objoff1: unlk a6 | Unlink stack frame
93 rts | Return to caller
94
95 .page
96| ------------------------------------------------------------------------------
97| objon(obj, line, num)
98| unsigned int obj, line, num;
99
100| Turn off access table bits for object 'obj'
101| at 'line' thru 'line'+'num'. Enables the object.
102| ------------------------------------------------------------------------------
103_objon: link a6,#0 | Link stack frames
104 move.w OBJ(a6),d1 | Get object bit number into d1
105 move.w LINE(a6),d2 | Get top line number
106 add.w d2,d2 | Convert to word offset
107 lea _v_actab,a0 | Get base address of access table
108 move.w 0(a0,d2),d0 | Get top line access word
109 bclr.l d1,d0 | Clear object bit
110 move.w d0,0(a0,d2) | Update word in access table
111 tst.w NUM(a6) | Number of lines = 0 ?
112 beq objon1 | Done if so
113
114 move.w NUM(a6),d2 | Get object depth
115 add.w LINE(a6),d2 | Add top line number
116 cmpi.w #SCSIZE,d2 | Bottom line >= screen height ?
117 bge objon1 | Done if so
118
119 add.w d2,d2 | Convert to word offset
120 move.w 0(a0,d2),d0 | Get bottom line access word
121 bclr.l d1,d0 | Clear object bit
122 move.w d0,0(a0,d2) | Update word in access table
123
124objon1: unlk a6 | Unlink stack frame
125 rts | Return to caller
126
127 .end
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