s3c4510b Samsung Semiconductor, Inc., s3c4510b Datasheet - Page 142

• Manufacturer Part Number: s3c4510b
• Description: 16/32-bit Risc Microcontroller
• Manufacturer: Samsung Semiconductor, Inc.

INSTRUCTION SET
DIVISION BY A CONSTANT
Division by a constant can often be performed by a short fixed sequence of shifts, adds and subtracts.
Here is an example of a divide by 10 routine based on the algorithm in the ARM Cookbook in both Thumb and
ARM code.
Thumb Code
udiv10
0
ARM Code
udiv10
3-100
MOV
LSR
SUB
LSR
ADD
LSR
ADD
LSR
ADD
LSR
ASL
ADD
ASL
SUB
CMP
BLT
ADD
SUB
MOV
SUB
SUB
ADD
ADD
ADD
MOV
ADD
SUBS
ADDPL
ADDMI
MOV
a2, a1
a3, a1, #2
a1, a3
a3, a1, #4
a1, a3
a3, a1, #8
a1, a3
a3, a1, #16
a1, a3
a1, #3
a3, a1, #2
a3, a1
a3, #1
a2, a3
a2, #10
%FT0
a2, #10
a2, a1, #10
a1, a1, a1, lsr #2
a1, a1, a1, lsr #4
a1, a1, a1, lsr #8
a1, a1, a1, lsr #16
a1, a1, lsr #3
a3, a1, a1, asl #2
a2, a2, a3, asl #1
a1, a1, #1
a2, a2, #10
pc, lr
a1, #1
pc, lr
; Take argument in a1 returns quotient in a1,
; remainder in a2
; Take argument in a1 returns quotient in a1,
; remainder in a2
S3C4510B