![Samsung S3C2501X Скачать руководство пользователя страница 153](http://html.mh-extra.com/html/samsung/s3c2501x/s3c2501x_user-manual_340828153.webp)
INSTRUCTION SET
S3C2501X
3-62
Multiplication by 6
ADD
Ra,Ra,Ra,LSL #1
; Multiply by 3
MOV
Ra,Ra,LSL#1
; and then by 2
Multiply by 10 and add in extra number
ADD
Ra,Ra,Ra,LSL#2
; Multiply by 5
ADD
Ra,Rc,Ra,LSL#1
; Multiply by 2 and add in next digit
General recursive method for Rb := Ra*C, C a constant:
1. If C even, say C = 2^n*D, D odd:
D=1:
MOV Rb,Ra,LSL #n
D<>1:
{Rb := Ra*D}
MOV
Rb,Rb,LSL #n
2. If C MOD 4 = 1, say C = 2^n*D+1, D odd, n>1:
D=1:
ADD Rb,Ra,Ra,LSL #n
D<>1:
{Rb := Ra*D}
ADD
Rb,Ra,Rb,LSL #n
3. If C MOD 4 = 3, say C = 2^n*D-1, D odd, n>1:
D=1:
RSB Rb,Ra,Ra,LSL #n
D<>1:
{Rb := Ra*D}
RSB
Rb,Ra,Rb,LSL #n
This is not quite optimal, but close. An example of its non-optimality is multiply by 45 which is done by:
RSB
Rb,Ra,Ra,LSL#2
; Multiply by 3
RSB
Rb,Ra,Rb,LSL#2
; Multiply by 4*3-1 = 11
ADD
Rb,Ra,Rb,LSL# 2
; Multiply by 4*11+1 = 45
rather than by:
ADD
Rb,Ra,Ra,LSL#3
; Multiply by 9
ADD
Rb,Rb,Rb,LSL#2
; Multiply by 5*9 = 45
Содержание S3C2501X
Страница 1: ...S3C2501X 32 BIT RISC MICROPROCESSOR USER S MANUAL Revision 1 查询S3C2501X供应商 捷多邦 专业PCB打样工厂 24小时加急出货 ...
Страница 18: ......
Страница 275: ...MEMORY CONTROLLER S3C2501X 5 60 NOTES ...
Страница 289: ...I2C CONTROLLER S3C2501X 6 14 NOTES ...
Страница 373: ...GDMA CONTROLLER S3C2501X 9 24 NOTES ...
Страница 435: ...I O PORTS S3C2501X 12 12 NOTES ...
Страница 463: ...ELECTRICAL DATA S3C2501X 15 6 NOTES ...