Clean up codehandler a little; stash msr on stack to preserve

This commit is contained in:
booto 2018-02-03 13:07:25 +08:00
parent 1264daae9b
commit aae8634a58
3 changed files with 18 additions and 9 deletions

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7
docs/codehandler.ld Normal file
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@ -0,0 +1,7 @@
OUTPUT_FORMAT(binary)
OUTPUT(codehandler.bin)
SECTIONS
{
. = 0x80001800;
.text : { *(.text) }
}

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@ -21,6 +21,8 @@
#SOFTWARE. #SOFTWARE.
#Based off of codehandleronly.s from Gecko OS source code. #Based off of codehandleronly.s from Gecko OS source code.
# Example command to build:
# powerpc-elf-gcc -mpowerpc -mpaired -mbig codehandler.s -nostartfiles -nodefaultlibs -nostdlib -T codehandler.ld -o codehandler.bin
.text .text
#Register Defines #Register Defines
@ -42,11 +44,11 @@ cheatdata:
.space 39*4 .space 39*4
_start: _start:
stwu r1,-168(r1) # stores sp stwu r1,-172(r1) # stores sp
stw r0,8(r1) # stores r0 stw r0,8(r1) # stores r0
mflr r0 mflr r0
stw r0,172(r1) # stores lr stw r0,176(r1) # stores lr
mfcr r0 mfcr r0
stw r0,12(r1) # stores cr stw r0,12(r1) # stores cr
@ -60,6 +62,8 @@ _start:
stmw r3,24(r1) # saves r3-r31 stmw r3,24(r1) # saves r3-r31
mfmsr r25 mfmsr r25
stw r25,168(r1) # save msr
ori r26,r25,0x2000 #enable floating point ? ori r26,r25,0x2000 #enable floating point ?
andi. r26,r26,0xF9FF andi. r26,r26,0xF9FF
mtmsr r26 mtmsr r26
@ -70,18 +74,17 @@ _start:
lis r31,_start@h #0x8000 lis r31,cheatdata@h #0x8000
lis r20, 0xCC00 lis r20, 0xCC00
lhz r28, 0x4010(r20) lhz r28, 0x4010(r20)
ori r21, r28, 0xFF ori r21, r28, 0xFF
sth r21, 0x4010(r20) # disable MP3 memory protection sth r21, 0x4010(r20) # disable MP3 memory protection
mflr r29
lis r15, codelist@h lis r15, codelist@h
ori r15, r15, codelist@l ori r15, r15, codelist@l
ori r7, 31, cheatdata@l # set pointer for storing data (before the codelist) ori r7, r31, cheatdata@l # set pointer for storing data (before the codelist)
lis r6,0x8000 # default base address = 0x80000000 (code handler) lis r6,0x8000 # default base address = 0x80000000 (code handler)
@ -101,17 +104,16 @@ _start:
addi r15,r15,8 addi r15,r15,8
b _readcodes b _readcodes
_exitcodehandler: _exitcodehandler:
mtlr r29
resumegame:
sth r28,0x4010(r20) # restore memory protection value sth r28,0x4010(r20) # restore memory protection value
lfd f2,152(r1) # loads f2 lfd f2,152(r1) # loads f2
lfd f3,160(r1) # loads f3 lfd f3,160(r1) # loads f3
lwz r25,168(r1)
mtmsr r25 mtmsr r25
lwz r0,172(r1) lwz r0,176(r1)
mtlr r0 # restores lr mtlr r0 # restores lr
lwz r0,12(r1) lwz r0,12(r1)
@ -127,7 +129,7 @@ resumegame:
lwz r0,8(r1) # loads r0 lwz r0,8(r1) # loads r0
addi r1,r1,168 addi r1,r1,172
isync isync