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1.1 maekawa 1: TITLE PC graphics module
2: ; uses LINEPROC.MAC
3:
4: ; Michael Gordon - 8-Dec-86
5: ;
6: ; Certain routines were taken from the Hercules BIOS of Dave Tutelman - 8/86
7: ; Others came from pcgraph.asm included in GNUPLOT by Colin Kelley
8: ;
9: ; modified slightly by Colin Kelley - 22-Dec-86
10: ; added header.mac, parameterized declarations
11: ; added dgroup: in HVmodem to reach HCh_Parms and HGr_Parms - 30-Jan-87
12: ;
13: ; modified and added to for use in plot(3) routines back end.
14: ; Gil Webster.
15: ;
16: ; Assemble with masm ver. 4.
17:
18: include header.mac
19:
20: if1
21: include lineproc.mac
22: endif
23:
24: GPg1_Base equ 0B800h ; Graphics page 1 base address
25:
26: extrn _inter:far
27:
28: _text segment
29:
30: public _PC_line, _PC_color, _PC_mask, _PC_curloc, _PC_puts, _Vmode
31: public _erase, _save_stack, _ss_interrupt
32:
33: pcpixel proc near
34: ror word ptr linemask,1
35: jc cont
36: ret
37: cont:
38: push ax
39: push bx
40: push cx
41: push dx
42: push bp
43: mov cx,ax ; x
44: mov dx,bx ; y
45: mov ah,0ch ; ah = write pixel
46: mov al,byte ptr color
47:
48: mov bh, 0 ; page 0
49: int 10h
50: pop bp
51: pop dx
52: pop cx
53: pop bx
54: pop ax
55: ret
56: pcpixel endp
57:
58: lineproc _PC_line, pcpixel
59:
60: ;
61: ; erase - clear page 1 of the screen buffer to zero (effectively, blank
62: ; the screen)
63: ;
64: beginproc _erase
65: push es
66: push ax
67: push cx
68: push di
69: mov ax, GPg1_Base
70: mov es, ax
71: xor di, di
72: mov cx, 4000h
73: xor ax, ax
74: cld
75: rep stosw ; zero out screen page
76: pop di
77: pop cx
78: pop ax
79: pop es
80: ret
81: _erase endp
82:
83: beginproc _PC_color
84: push bp
85: mov bp,sp
86: mov al,[bp+X] ; color
87: mov byte ptr color,al
88: pop bp
89: ret
90: _PC_color endp
91:
92: beginproc _PC_mask
93: push bp
94: mov bp,sp
95: mov ax,[bp+X] ; mask
96: mov word ptr linemask,ax
97: pop bp
98: ret
99: _PC_mask endp
100:
101: beginproc _Vmode
102: push bp
103: mov bp,sp
104: push si
105: push di
106: mov ax,[bp+X]
107: int 10h
108: pop di
109: pop si
110: pop bp
111: ret
112: _Vmode endp
113:
114: beginproc _PC_curloc
115: push bp
116: mov bp,sp
117: mov dh, byte ptr [bp+X] ; row number
118: mov dl, byte ptr [bp+X+2] ; col number
119: mov bh, 0
120: mov ah, 2
121: int 10h
122: pop bp
123: ret
124: _PC_curloc endp
125:
126: ;
127: ; thanks to watale!broehl for finding a bug here--I wasn't pushing BP
128: ; and reloading AH before INT 10H, which is necessary on genuine IBM
129: ; boards...
130: ;
131: beginproc _PC_puts
132: push bp
133: mov bp,sp
134: push si
135: mov bl,byte ptr color
136: mov si,[bp+X] ; offset
137:
138: ifdef LARGE_DATA
139: mov es,[bp+X+2] ; segment if large or compact data model
140: endif
141:
142: puts2:
143:
144: ifdef LARGE_DATA
145: mov al,es:[si]
146: else
147: mov al,[si]
148: endif
149: or al,al
150: jz puts3
151: mov ah,0eh ; write TTY char
152: int 10h
153: inc si
154: jmp short puts2
155: puts3: pop si
156: pop bp
157: ret
158: _PC_puts endp
159:
160:
161: ; int kbhit();
162: ; for those without MSC 4.0
163: ; Use BIOS interrupt 16h to determine if a key is waiting in the buffer.
164: ; Return nonzero if so.
165: ;
166:
167: beginproc _kbhit
168: mov ah, 1 ; function code 1 is keyboard test
169: int 16h ; keyboard functions
170: jnz kbfin ; Exit if char available
171: xor ax, ax ; No char: return zero.
172: kbfin: ret
173: _kbhit endp
174:
175:
176: ; _save_stack and _ss_interrupt are needed due to a bug in the MSC 4.0
177: ; code when run under MS-DOS 3.x. Starting with 3.0, MS-DOS automatically
178: ; switches to an internal stack during system calls. This leaves SS:SP
179: ; pointing at MS-DOS's stack when the ^C interrupt (INT 23H) is triggered.
180: ; MSC should restore its own stack before calling the user signal() routine,
181: ; but it doesn't.
182: ;
183: ; Presumably this code will be unnecessary in later releases of the compiler.
184: ;
185:
186: ; _save_stack saves the current SS:SP to be loaded later by _ss_interrupt.
187: ;
188:
189: beginproc _save_stack
190: mov ax,ss
191: mov cs:save_ss,ax
192: mov ax,sp
193: mov cs:save_sp,ax
194: ret
195: _save_stack endp
196:
197:
198: ; _ss_interrupt is called on ^C (INT 23H). It restores SS:SP as saved in
199: ; _save_stack and then jumps to the C routine interrupt().
200: ;
201: beginproc _ss_interrupt
202: cli ; no interrupts while the stack is changed!
203: mov ax,-1 ; self-modifying code again
204: save_ss equ this word - 2
205: mov ss,ax
206: mov sp,-1 ; here too
207: save_sp equ this word - 2
208: sti
209: jmp far ptr _inter; now it's safe to call the real routine
210: _ss_interrupt endp
211:
212:
213: _text ends
214:
215:
216: const segment
217: linemask dw -1
218: color db 1
219: const ends
220:
221: end