Stack Addressing Modes (Sp) - Texas Instruments TMS320C28x Reference Manual

5.5 Stack Addressing Modes (SP)

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