Texas Instruments TMS320C28x, Reference Manual

Page: 133 / 695

Stack Addressing Modes (SP)
5-9 C28x Addressing Modes
5.5 Stack Addressing Modes (SP)
AMODE ”loc16/loc32” Syntax Description
0
*−SP[6bit]
32bitDataAddr(31:16) = 0x0000
32bitDataAddr(15:0) = SP
− 6bit
Note: The 6-bit offset value is subtracted from the current 16-bit SP register val-
ue. The offset value enables 0 to 63 words to be addressed relative to the
current SP register value.
Example(s):
ADD AL,*−SP[5] ; Add 16-bit contents from stack location
; −5 words from top of stack to AL register
MOV *-SP[8],AL ; Store 16-bit AL register to stack location
; -8 words from top of stack
ADDL ACC,*−SP[12] ; Add 32-bit contents from stack location
; −12 words from top of stack to ACC register.
MOVL *-SP[34],ACC ; Store 32-bit ACC register to stack location
; −34 words from top of stack
AMODE ”loc16/loc32” Syntax Description
X
*SP++
32bitDataAddr(31:16) = 0x0000
32bitDataAddr(15:0) = SP
if(loc16), SP = SP + 1
if(loc32), SP = SP + 2
Example(s):
MOV *SP++,AL ; Push contents of 16-bit AL register onto top
; of stack
MOVL *SP++,P ; Push contents of 32-bit P register onto top
; of stack
AMODE ”loc16/loc32” Syntax Description
X
*−−SP
if(loc16), SP = SP − 1
if(loc32), SP = SP − 2
32bitDataAddr(31:16) = 0x0000
32bitDataAddr(15:0) = SP
Example(s):
ADD AL,*−−SP ; Pop contents from top of stack and add to 16-bit
; AL register
MOVL ACC,*−−SP ; Pop contents from top of stack and store in
; 32-bit ACC register
Note: This addressing mode can only access the lower 64K of data address space on the C28x device.