Microsoft Word Huong dan thuc hanh mips asm tren pcspim doc
tải về 0.57 Mb. Chế độ xem pdf
|
MIPSSSS, 5
- Điều hướng trang này:
- 5.5 Các ví dụ xử lý chuỗi, xử lý mảng
| 5.4 Các lệnh nhảy
Thiết lập các tham số trong menu Simulator -> Settings: Bare Machine ON, Allow Pseudo Instructions OFF, Load Trap File OFF, Delayed Branches ON, Delayed Loads ON, Mapped IO OFF, Quiet OFF j bne slti beq bltz sltu bgez slt sltiu ## Find the Significant bits in a pattern ## The significant bits are the leftmost one bit and ## all its to its right ## Approach: Count the number of right shifts needed ## before the pattern becomes all zeros ## ## Register Use: ## $7 --- shift count ## $8 --- the bit pattern, 0x00298D7D for example. .text .globl main main: ori $8,$0,0x0029 # load $8 with the pattern sll $8,$8,16 # shift into MSBs ori $8,$8,0x8D7D # or in the LSBs ## copy $9 to memory in big-endian form ## ## Register Use: ## $8 --- first byte of the tape block ## $9 --- 4-byte integer .text .globl main main: lui $9,0x1234 # put data in $9 ori $9,0x5678 # lui $8,0x1000 # $8 is base register sb $9,3($8) # least significant byte srl $9,$9,8 # move next byte to low order sb $9,2($8) # bits 8-15 srl $9,$9,8 # move next byte to low order sb $9,1($8) # bits 16-23 srl $9,$9,8 # move next byte to low order sb $9,0($8) # most significant byte .data tape: # base register points here .space 1024 # tape buffer (1K bytes) ## End of file 5.5 Các ví dụ xử lý chuỗi, xử lý mảng Các lệnh đã biết cho đến giờ: Thiết lập các tham số trong menu Simulator -> Settings: Bare Machine ON, Allow Pseudo Instructions OFF, Load Trap File OFF, Delayed Branches ON, Delayed Loads ON, Mapped IO OFF, Quiet OFF loop: beq $8,$0,exit # done when pattern == 00 sll $0,$0,0 # delay or nop after a branch # or jump instruction srl $8,$8,1 # shift right one bit addu $7,$7,1 # increment shift count j loop # repeat sll $0,$0,0 exit: j exit # sponge for extra cycles sll $0,$0,0 ## End of file add div mflo slt, slti addi divu mult sltu, sltiu addiu j multu sra addu lb nor srl and lbu or sub andi lh ori subu beq lhu sb sw bgez lui sh xor bltz lw sll xori bne mfhi ## To Lower Case ## ## ## Write a program that converts the string to all lower case ## characters. Do this by adding 0x20 to each character in the string. ## Register Use: ## ## $8 --- current character ## $10 --- character pointer |