IBM 5150 Technical Reference page 182

LOC OBJ
LINE SOURCE
F4!F 7500 4262
JHZ R.
; YES. XOR THE DOT
F441 F604 4263 HOT AH
, SET THE MASK TO REMOVE THE
F443 22CC 4264
.HO
CL,AH
; INDICATED BITS
F445 DAtI 4265
00
Al,CL ; OR IN THE NEW VAlUE OF THOSE BITS
F447
4266
Ill: I FINISH_DOT
F447 268804
4267
HOV
ES:ISI1.Al I RESTORE THE BYTE IN MEI'tORY
F44.1. 58 4268
POP
,X
F448 E977FD
4269
JHP VIDEO_RETURN
; RETURN FROI1 VIDEO 10
1"'""""\
F44£ 4270 R2: I XOR_DOT
F44E UtI 42.71
XOR
Al,CL ; EXCLUSIVE OR THE DOTS
0'
F450 EBFS 4272 JHP I FINISH UP THE WRITING
4273
WRITE_DOT EHOP
4274
;------------------------------------------------------- ­
4275 I THIS SUBROUTINE DETERMINES THE REGEN BYTE LOCATION
4276 ; OF THE INDICATED ROW COLUMN VALUE IN GRAPHICS MODE.
4277
I ENTRY - ­
4278
OX
=
ROW VALUE (0-199)
4279
ex =
COll.lNH VALUE 10-639)
4280
EXIT - ­
4281 51
=
OFFSET INTO REGEN BUFFER FOR BYTE OF INTEREST
4282
I
AH
=
MASK TO STRIP OFF THE SITS Of INTEREST
4283
CL
=
BITS TO SHIfT TO RIGHT JUSTIfY THE MASK IN AH
4284
I
DH
= •
BITS IN RESULT
4285
1------------------------------------------------------- ­
F452
4286 03 PROC NEAR
F452 53
4287 PUSH BX
1 SAVE BX D~ING OPERATION
F453 50
428S PUSH AX 1
WILL SAVE
.u
DURING OPERATION
4289
4290
1-----
DETERMINE 1ST BYTE IN IDICATED ROW BY HULTIPlYING ROW VALUE BY 40
4291
BIT OF ROW DETERMINES EVEN/ODD. SO BYTESIROW
J----- (
lOW
4292
F454 B028
4293 HOV Al.40
F456 52
4294 PUSH OX
, SAVE ROW VALUE
F457 80E2FE 4295
.NO
DL.OFEH
J STRIP OFF DOD/EVEN BIT
F45A F6E2
4296 HUl
Ol J
AX HAS ADDRESS Of 1ST BYTE
4297
,
OF It-CICATEO ROW
F45C SA
4298 POP OX ; RECOVER IT
F45D F6C201
4299 TEST Dl.l ; TEST FOR EVENIODD
F460 7403
4300 JZ I JUMP IF EVEN ROW
F462 050020
4301
'00
AX.2000H I OFFSET TO LOCATION OF 000 ROWS
F465 4302
R4:
J EVEN_ROW
F465 8BFO 4303
HOV SI.AX 1
MOVE POINTER TO 51
F467 58
4304 POP AX ; RECOVER AL VALUE
F468 8BDI
4305
HOV OX.CX ; COLUMN VAlUE TO OX
4306
4307
1-----
DETERMINE GRAPHICS HaDE CURRENTLY IN EFFECT
4308
4309
r""\
R'
1--------------------------------------------------------------.­
4310 ; SET UP THE REGISTERS ACCORDING TO THE HOOE
4311
CH
=
I1ASK FOR LOW OF COLlR1H ADDRESS ( 7/3 FOR HIGH/NED RES)
4312 CL :::: • OF ADDRESS BITS IN COLUMN VALUE ( 312 FOR H/NI
4313
I
BL
=
HASK TO SElECT BITS FROM POINTED BYTE ISOH/COH fOR H/N)
4314
I
BH
=
NUMBER OF VAlID BITS IN POINTED BYTE (
112
fOR HIH)
4315
1--- --- - - -- - -------- - ------ - -- - ------ - - ---- -- - ------ -------- - -- - ­
4316
F46A BBC002 4317
I10V BX.2tOH
F46D B90203 431S
Mev
CX.302H ; SET PARHS FOR MED RES
F470 803E490006 4319
CHP CRT.HODE.6
F475 7206 4320
JC
.5
; HANOLE
If
MED ARES
F477 BB8001 4321
HOV BX.180H
F47A B90307
4322 HOV
CX.703H
; SET PARHS fOR HIGH RES
4323
4324
1-----
DETERMINE BIT OFFSET IN BYTE FROM COLUHH MASK
4325
F47D
4326 RS:
F47D 22EA 4327
ANI)
CH.DL
1
ADDRESS OF PEL WITHIN BYTE TO CH
4328
4329
J ----- DETERMINE BYTE OFFSET FOR THIS LOCATION IN COlUHN
4330
r"'\
F47F 03EA
4331 SHO DX.CL ; SHIFT BY CORRECT AMOUNT
F481 03F2 4332 .DO SI,OX I INCREMENT THE POINTER
F483 8AF7
4333 HOY OH,SH ; GET THE • OF BITS- IN RESULT TO OH
4334
4335
1-----
HULTIPL'f BH (VALID BITS IN BYTE) BY CH (BIT OFFSEll
433&
F485 ZAC9 4337
SUB CL.CL
; ZERO INTO STORAGE LOCATION
F487
'3]8 R6:
System BIOS 5-89