Motorola DSP56000 Manual page 539

SBC
Operation:
D–S–C D (parallel move)
Description: Subtract the source operand S and the carry bit C of the condition code
register from the destination operand D and store the result in the destination accumula-
tor. Long words (48 bits) may be subtracted from the (56-bit) destination accumulator.
Note: The carry bit is set correctly for multiple-precision arithmetic using long-word oper-
ands if the extension register of the destination accumulator (A2 or B2) is the sign exten-
sion of bit 47 of the destination accumulator (A or B).
Example:
:
MOVE L:<$0,X
MOVE L:<$1,A
MOVE L:<$2,Y
SUB X,A L:<$3,B
SBC YB A10,L:<$4
MOVE B10,L:<$5
:
Before Execution
A
$00:000000:000000
X
$800000:000000
B
$00:000000:000003
Y
$000000:000001
A - 270
INSTRUCTION DESCRIPTIONS
Subtract Long with Carry
Assembler Syntax:
;get a 48-bit LS long-word operand in X
;get other LS long word in A (sign ext.)
;get a 48-bit MS long-word operand in Y
;sub. LS words; get other MS word in B
;sub. MS words with carry; save LS dif.
;save MS difference
INSTRUCTION SET DETAILS
SBC S,D (parallel move)
After Execution
A
$00:800000:000000
X
$800000:000000
B
$00:000000:000001
Y
$000000:000001
SBC
MOTOROLA