標(biāo)題: ARM9之2440時(shí)鐘 [打印本頁(yè)]

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作者: xuwei    時(shí)間: 2015-6-13 16:12
標(biāo)題: ARM9之2440時(shí)鐘
其實(shí)ARM9并沒有什么了不起的，和ARM7，6基本是一樣的，裸奔起來并沒有什么不同，個(gè)人感覺八錯(cuò)！倒是那萬(wàn)能的C語(yǔ)言卻是真的！

1. U32 val;
   
2. U8 m, p, s;
   
3. val = rMPLLCON;
   
4. m = (val>>12)&0xff;
   
5. p = (val>>4)&0x3f;
   
6. s = val&3;
   
7. 
   
8. //(m+8)*FIN*2 不要超出32位數(shù)!
   
9. FCLK = ((m+8)*(FIN/100)*2)/((p+2)*(1<<s))*100;
   
10. val = rCLKDIVN;
    
11. m = (val>>1)&3;
    
12. p = val&1;       
    
13. val = rCAMDIVN;
    
14. s = val>>8;
    
15. switch (m) {
    
16. case 0:
    
17. HCLK = FCLK;
    
18. break;
    
19. case 1:
    
20. HCLK = FCLK>>1;
    
21. break;
    
22. case 2:
    
23. if(s&2)
    
24. HCLK = FCLK>>3;
    
25. else
    
26. HCLK = FCLK>>2;
    
27. break;
    
28. case 3:
    
29. if(s&1)
    
30. HCLK = FCLK/6;
    
31. else
    
32. HCLK = FCLK/3;
    
33. break;
    
34. }
    
35. if(p)
    
36. PCLK = HCLK>>1;
    
37. else
    
38. PCLK = HCLK;
    
39. if(s&0x10)
    
40. cpu_freq = HCLK;
    
41. else
    
42. cpu_freq = FCLK;
    
43. val = rUPLLCON;
    
44. m = (val>>12)&0xff;
    
45. p = (val>>4)&0x3f;
    
46. s = val&3;
    
47. UPLL = ((m+8)*FIN)/((p+2)*(1<<s));
    
48. UCLK = (rCLKDIVN&8)?(UPLL>>1):UPLL;

復(fù)制代碼

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