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!
! 12/31/96
! A.B. Maccabe
!
! read 10 characters from the UART and send them back to the UART
! -- no buffering, quit if we get an overrun
!
UARTSTATUS = 0X140000
UARTCREG = 0x140000
UARTTXREG = 0x140004
UARTRXREG = 0x140004
NCHARS = 30
.data
ovr_msg: .asciz "Overrun error detected, quit\n"
.text
.global start
start:
set UARTSTATUS, %l0
! set the UART control register -- disable interrupts and set the
! rx/tx rate fairly low
set 0x40, %l2
st %l2, [%l0]
set NCHARS, %l2
top:
! wait for a character to appear
poll_rcv:
ld [%l0], %l1
! check for overrun error
andcc %l1, 4, %g0
be chk_rcv
nop
! overrun -- print a message and exit
set ovr_msg, %o0
ta 6
ta 0
chk_rcv:
! check for a received character
andcc %l1, 2, %g0
be top
nop
! get the character
ld [%l0 + 4], %l3
! wait for transmit reg empty
poll_snd:
ld [%l0], %l1
andcc %l1, 1, %g0
be poll_snd
nop
! send the character to the UART
st %l3, [%l0+4]
deccc %l2
bne top
nop
ta 0
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