Re: [U-Boot-Users] what means this symbol "@"?
Thank you!Now I understand it. lis r1,value =addis r1,0,value
----- Original Message ----- From: "Udi Finkelstein" udif@bigfoot.com To: "seaman" okisoftxman@hotmail.com Sent: Thursday, May 08, 2003 4:42 PM Subject: Re: [U-Boot-Users] what means this symbol "@"?
My guess is that "@h" means a 16-bit constant made of the upper 16-bot of CFG_IMMR.
It took me a lot of time to find what "lis" is. I couldn't find it in either the IBM arch. manual I had, or the MPC823 manual. Only after I looked at the obcode, I found that this is actually something like a private case of the add immediate instruction or something like that, where the 1st argument is a constant 0. This means that lis loads a register by taking a 16-bit constant and putting it in the upper 16-bit, and resetting the lower 16-bit (because that's 0 + arg<<16). Since CFG_IMMR is on a 64KB boundary, its lower 16 bitare zero, so "lis r3,CFG_IMMR@h" simply loads CFG_IMMR to r3.
Udi
seaman wrote:
In u-boot/cpu/mpc8xx/start.S,I usually find this symbol "@",such as followed:
_start: lis r3, CFG_IMMR@h /* position IMMR */ mtspr 638, r3 li r21, BOOTFLAG_COLD /* Normal Power-On: Boot from FLASH */ b boot_cold
what does it means? Thank you!
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seaman