IBM PC CONVERTIBLE Technical Reference page 203

01BE
01BE
01CO
01C3
01C5
01C8
01CC
01CC
01CE
0100
0102
0105
0105
0107
0109
01DB
OlDD
01DF
OlEl
01E3
01E5
01E5
01E8
01EB
OlEO
01FO
01F2
8A EO
80 FB 00
74 07
80 CC 20
INPUT: ES:DI CONTAINS POINTER TO BYTE IN USERS STORAGE FOR
EVENT DETERMINATION (FOR AL:01-04)
- 0 R -
OX CONTAINS ADDRESS OF
1/0
PORT ADDRESS TO BE READ FOR
EVENT DETERMINATION (FOR AL:11-14)
AL - EVENT TYPE CODE
00 - RETURN AFTER ANY EVENT HAS OCCURRED
01 - COMPARE: RETURN I F EQUAL
02 - COMPARE: RETURN I F NOT EQUAL
03 - TEST: RETURN I F NOT ZERO
04 - TEST: RETURN I F ZERO
11-14 - SAME FUNCTION AS ABOVE EXCEPT OX CONTAINS
1/0
PORT ADDRESS FOR EVENT DETERMINATION
BH - CONDITION COMPARE OR MASK VALUE
BL - TIMEOUT VALUE (IN 55 MSEC UNITS)
BL : 0 - NO TIME LIMIT
OUTPUT: CARRY FLAG: SET - TIMEOUT REACHED
CLEAR - EVENT OCCURRED
REGISTERS
MODIFIED: AX
RESTRICTIONS: THIS ROUTINE WILL ENABLE PROC IRPTS NO TIMEOUT WILL
OCCUR IF TMR 0 IS NOT ENABLED WAITING ON NMI IRPTS
I S NOT ALLOWED.
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EXLEVENT PROC NEAR
MOV AH,AL SAVE TYPE CODE
CMP BL,O NO TIME LIMIT FOR TIMEOUT?
JE EXLWTl NO, GO CHECK FOR WAIT TYPE
OR AH,20H YES, SET NO TIMEOUT FLAG
88 IE 007B R MOV EVENLTIM_OUT ,BL SAVE TIMEOUT VALUE
EXLWTl:
24 OF AND AL ,OFH
SAVE ONLY TYPE
3C 00 CMP AL,O
WAIT ON ANY EVENT?
75 03 JNE EXLWT2
NO, CHECK FOR SPECIFIC EVENT
E9 0259 JMP ANLWAIT YES, WA IT ON ANY EVNT TO RET
EXLWT2 :
3C 01 CMP AL,Ol
COMPARE, RETURN EQUAL?
74 64 JE CEQ_WAIT
3C 02 CMP AL,02
74 44 JE CNEQ_WAIT COMPARE , RETURN NOT EQUAL
3C 03 CMP AL,03
74 24 JE TNLWAIT
TEST, RETURN NOT ZERO
3C 04 CMP AL,04
75 1C JNE I NY-EVENT I F NOT 4 THEN INVALID EVENT
TEST, RETURN I F ZERO
TLWAIT:
E8 026B R CALL
PREP_WAIT PREPARE FOR WAIT
F6 C4 10 TEST AH,10H TEST FOR
110
PORT READ
75 08 JNZ TLWTl
26: 84 3D
TEST BYTE PTR ES: [01], BH
74 70 JZ
WAIT_DONE RETURN I F ZERO
EB 06 90 JMP TLWT2
2-178 ROM BIOS