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MIPS: xburst: simplify relocation offset calculation

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The current code uses four instructions and a
temporary register to calculate the relocation
offset and to adjust the gp register.

The relocation offset can be calculated directly
from the CONFIG_SYS_MONITOR_BASE constant and from
the destination address. The resulting offset can
be used to adjust the gp pointer.

This approach makes the code a bit simpler because
it needs two instructions only.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Cc: Daniel Schwierzeck <daniel.schwierzeck@googlemail.com>
Cc: Xiangfu Liu <xiangfu@openmobilefree.net>
This commit is contained in:
Gabor Juhos 2013-01-30 04:51:06 +00:00 committed by Daniel Schwierzeck
parent 025f2b3380
commit 6d86227880
1 changed files with 3 additions and 9 deletions
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12
arch/mips/cpu/xburst/start.S
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@ -64,19 +64,13 @@ relocate_code:
move sp, a0 # set new stack pointer
li t0, CONFIG_SYS_MONITOR_BASE
sub t6, a2, t0 # t6 <-- relocation offset
la t3, in_ram
lw t2, -12(t3) # t2 <-- uboot_end_data
move t1, a2
/*
* Fix $gp:
*
* New $gp = (Old $gp - CONFIG_SYS_MONITOR_BASE) + Destination Address
*/
move t6, gp
sub gp, CONFIG_SYS_MONITOR_BASE
add gp, a2 # gp now adjusted
sub t6, gp, t6 # t6 <-- relocation offset
add gp, t6 # adjust gp
/*
* t0 = source address