mmu.s

ARM嵌入式系统开发--软件设计与优化随书源代码。开发环境asm+c

;  ____________________________________________________________________
; 
;  Copyright (c) 2002, Andrew N. Sloss, Chris Wright and Dominic Symes
;  All rights reserved.
;  ____________________________________________________________________
; 
;  NON-COMMERCIAL USE License
;  
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;  modification, are permitted provided that the following conditions 
;  are met: 
;  
;  1. For NON-COMMERCIAL USE only.
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;  4. All advertising materials mentioning features or use of this 
;     software must display the following acknowledgement:
; 
;     This product includes software developed by Andrew N. Sloss,
;     Chris Wright and Dominic Symes. 
; 
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   AREA MMU, CODE

   EXPORT mmuChangeControl
   EXPORT changeDomAccess   
   EXPORT mmuSetTTB   
   EXPORT mmuFlushTLB   
   EXPORT mmuFlushCache     

mmuFlushCache
     MOV r0, #0
     MCR p15,0,r0,c7,c5,0   ; flush i Cache
     MCR p15,0,r0,c7,c6,0   ; flush d cache
     MOV pc, lr

;-----------------
; Change Domain Access Register Values
; int changeDomAccess(unsigned value, unsigned mask)
;-----------------
changeDomAccess
   MVN r2, r1                ; invert mask
   BIC r3, r0, r2            ; clear values that are not masked
   CMP r3, r0
   BNE ErrorControl          ; value outside of mask set 
   MRC p15, 0, r3, c3, c0, 0 ; get domain access register values
   BIC r3, r3, r1            ; mask off bits that change
   ORR r3, r3, r0            ; set bits that change
   MCR p15, 0, r3, c3, c0, 0 ; set domain access register values
   MOV r0, #0
   MOV pc, lr

mmuSetTTB
    MCR p15, 0, r0, c2, c0, 0 ; Write TTB register with base address
    MOV pc, lr
mmuFlushTLB
    MOV r0, #0
    MCR p15, 0, r0, c8, c7, 0 ; flush both the TLBs
    MOV pc, lr
;-----------------
; Change Control Register Values
; int changeControl(unsigned value, unsigned mask)
;-----------------   
mmuChangeControl
   MVN r2, r1                ; invert mask
   BIC r3, r0, r2            ; clear values that are not masked
   CMP r3, r0
   BNE ErrorControl          ; value outside of mask set 
   MRC p15, 0, r3, c1, c0, 0 ; get control register values
   BIC r3, r3, r1            ; mask off bits that change
   ORR r3, r3, r0            ; set bits that change
   MCR p15, 0, r3, c1, c0, 0 ; set control register values
   MOV r0, #0
   MOV pc, lr


OutOfRange
   B OutOfRange               ; loop at error for debugging

ErrorControl
   b ErrorControl
ErrorPermission               ; Error Permission =4
   b ErrorPermission          ; debug test
   ADD r0, r0, #1
ErrorSize                     ; Error  Size = 3
   ADD r0, r0, #1
ErrorAddress                  ; Error  Address unaligned = 2
   ADD r0, r0, #1
ErrorRegion                   ; Error  Region not valid = 1
   ADD r0, r0, #1
   MOV pc, lr

   END