Indirect Addressing Modes
5-16
AMODE ”loc16/loc32” Syntax Description
X *0−− 32bitDataAddr(31:0) = XAR(ARP)
XAR(ARP) = XAR(ARP) − AR0
Note: The lower 16-bits of XAR0 are subtracted from the selected 32-bit regis-
ter. Upper 16-bits of XAR0 ignored. AR0 is treated as an unsigned 16-bit
value. Underflow into the upper 16-bits of XAR(ARP) can occur.
Example(s):
MOVL XAR2,#Array1+(N−1)*8 ; Load XAR2 with end address of Array1
MOVL XAR3,#Array2+(N−1)*2 ; Load XAR3 with end address of Array2
MOV @AR0,#4 ; Set AR0 to copy every fourth value from
; Array1 to Array2
MOV @AR1,#N−1 ; Load AR1 with loop count N
Loop:
NOP *,ARP2 ; Set ARP pointer to point to XAR2
MOVL ACC,*0−− ; Load ACC with location pointed to by
; XAR2, post−decrement XAR2 by AR0
NOP *,ARP3 ; Set ARP pointer to point to XAR3
MOVL *−−,ACC ; Store ACC into location pointed to by
; XAR3, post−decrement XAR3
NOP *,ARP1 ; Set ARP pointer to point to XAR1
XBANZ Loop,*−− ; Loop until AR1 == 0, post−decrement AR1
AMODE ”loc16/loc32” Syntax Description
1 *0−−,ARPn 32bitDataAddr(31:0) = XAR(ARP)
XAR(ARP) = XAR(ARP) − AR0
ARP = n
Note: The lower 16-bits of XAR0 are subtracted from the selected 32-bit regis-
ter. Upper 16-bits of XAR0 ignored. AR0 is treated as an unsigned 16-bit
value. Underflow into the upper 16-bits of XAR(ARP) can occur.
Example(s):
MOVL XAR2,#Array1+(N−1)*8 ; Load XAR2 with end address of Array1
MOVL XAR3,#Array2+(N−1)*2 ; Load XAR3 with end address of Array2
MOV @AR0,#4 ; Set AR0 to copy every fourth value from
; Array1 to Array2
MOV @AR1,#N−1 ; Load AR1 with loop count N
NOP *,ARP2 ; Set ARP pointer to point to XAR2
SETC AMODE ; Make sure AMODE = 1
.lp_amode ; Tell assembler that AMODE = 1
Loop:
MOVL ACC,*0−−,ARP3 ; Load ACC with location pointed to by
; XAR2, post−decrement XAR2 by AR0, set ARP
; pointer to point to XAR3
MOVL *−−,ACC,ARP1 ; Store ACC into location pointed to by
; XAR3, post−decrement XAR3, set ARP
; pointer to point to XAR1
XBANZ Loop,*−−,ARP2 ; Loop until AR1 == 0, post−decrement AR1,
; set ARP to point to XAR2
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