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Init performance fix

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Quite an embarrassing one. I search the stack for a known 4-byte value.
This search starts at the stack pointer and continues towards low
memory. Oops! I was searching nearly the entire address space.
This commit is contained in:
Elliot Nunn 2021-03-02 19:11:57 +08:00
parent a96d61eca7
commit c5947f2652
1 changed files with 2 additions and 2 deletions
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4
ChainLoader.a
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@ -56,8 +56,8 @@ ResumeAfterCopy
; We do this by scanning the stack for the return address of the original _Read. ; We do this by scanning the stack for the return address of the original _Read.
move.l $2AE,A0 ; A0 = ROMBase (lower limit) move.l $2AE,A0 ; A0 = ROMBase (lower limit)
lea $4000(A0),A1 ; A1 = ROMBase + a bit (upper limit) lea $4000(A0),A1 ; A1 = ROMBase + a bit (upper limit)
lea -2(SP),A2 move.l SP,A2
.loop subq.l #2,A2 ; A2 = where we search the stack .loop addq.l #2,A2 ; A2 = where we search the stack
move.l (A2),A3 ; A3 = potential return address move.l (A2),A3 ; A3 = potential return address
cmp.l A0,A3 ; lower limit check cmp.l A0,A3 ; lower limit check
bls.s .loop bls.s .loop