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https://github.com/elliotnunn/powermac-rom.git
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4c0e5221f1
These + and - characters in a branch mnemonic can cause the assembler to produce conditional branch instructions with that hint the branch predictor. The default for forward branches is -, and for backward branches is +. If a mnemonic is issued with the opposite sign, then bit 10 of the instruction (the LSB of the BO field) is set. My long-retired "ppcdisasm" script inserted these hints unconditionally, despite 98% of them not being required. The code is much cleaner now. I read in some old MPW release notes that PPCAsm and PPCLink together exhibit a quirk when linking conditional branches to imported symbols. PPCAsm always assembles these conditional branches as if they were forward branches (that is, a + hint will always set the hint bit, and a - hint will never). I hoped to use this property to divine whether the NanoKernel was linked from one or many assembly files, but I was frustrated by the lack of conditional branches between files.
179 lines
3.4 KiB
ArmAsm
179 lines
3.4 KiB
ArmAsm
Local_Panic set *
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b panic
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; kcRTASDispatch
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; Only major that hits the RTAS globals.
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; RTAS requires some specific context stuff.
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; > r1 = kdp
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; > r6 = some kind of place
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; > r7 = some kind of flags
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align 5
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kcRTASDispatch ; OUTSIDE REFERER
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lwz r8, 0x0908(r1)
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cmpwi r8, 0x00
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bne rtas_is_available
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li r3, -0x01
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b IntReturn
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rtas_is_available
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_Lock PSA.RTASLock, scratch1=r8, scratch2=r9
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mtcrf 0x3f, r7
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lwz r9, KDP.PA_ECB(r1)
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lwz r8, EWA.Enables(r1)
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stw r7, 0x0000(r6)
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stw r8, 0x0004(r6)
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bns cr6, kcRTASDispatch_0x5c
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stw r17, 0x0024(r6)
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stw r20, 0x0028(r6)
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stw r21, 0x002c(r6)
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stw r19, 0x0034(r6)
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stw r18, 0x003c(r6)
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lmw r14, 0x0038(r1)
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kcRTASDispatch_0x5c
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mfxer r8
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stw r13, 0x00dc(r6)
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stw r8, 0x00d4(r6)
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stw r12, 0x00ec(r6)
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mfctr r8
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stw r10, 0x00fc(r6)
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stw r8, 0x00f4(r6)
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ble cr3, kcRTASDispatch_0x8c
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lwz r8, 0x00c4(r9)
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mfspr r12, mq
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mtspr mq, r8
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stw r12, 0x00c4(r6)
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kcRTASDispatch_0x8c
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lwz r8, 0x0004(r1)
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stw r8, 0x010c(r6)
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stw r2, 0x0114(r6)
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stw r3, 0x011c(r6)
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stw r4, 0x0124(r6)
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lwz r8, 0x0018(r1)
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stw r5, 0x012c(r6)
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stw r8, 0x0134(r6)
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andi. r8, r11, 0x2000
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stw r14, 0x0174(r6)
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stw r15, 0x017c(r6)
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stw r16, 0x0184(r6)
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stw r17, 0x018c(r6)
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stw r18, 0x0194(r6)
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stw r19, 0x019c(r6)
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stw r20, 0x01a4(r6)
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stw r21, 0x01ac(r6)
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stw r22, 0x01b4(r6)
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stw r23, 0x01bc(r6)
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stw r24, 0x01c4(r6)
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stw r25, 0x01cc(r6)
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stw r26, 0x01d4(r6)
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stw r27, 0x01dc(r6)
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stw r28, 0x01e4(r6)
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stw r29, 0x01ec(r6)
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stw r30, 0x01f4(r6)
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stw r31, 0x01fc(r6)
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bnel major_0x03e18_0xb4
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stw r11, 0x00a4(r6)
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mr r27, r3
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addi r29, r1, 800
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bl PagingFunc3
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beql Local_Panic
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rlwimi r3, r31, 0, 0, 19
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lhz r8, 0x0004(r3)
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cmpwi r8, 0x00
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beq kcRTASDispatch_0x14c
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slwi r8, r8, 2
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lwzx r27, r8, r3
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addi r29, r1, 800
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bl PagingFunc3
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beql Local_Panic
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lwzx r9, r8, r3
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rlwimi r9, r31, 0, 0, 19
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stwx r9, r8, r3
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li r9, 0x00
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sth r9, 0x0004(r3)
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dcbf r8, r3
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kcRTASDispatch_0x14c
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li r9, 0x04
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dcbf r9, r3
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sync
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isync
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lwz r4, 0x090c(r1)
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mfmsr r8
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andi. r8, r8, 0x10cf
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mtmsr r8
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isync
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mr r28, r3
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lwz r9, 0x0908(r1)
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bl rtas_make_actual_call
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mfsprg r1, 0
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lwz r6, -0x0014(r1)
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clrlwi r29, r28, 0x14
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subfic r29, r29, 0x1000
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lhz r27, 0x0f4a(r1)
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kcRTASDispatch_0x190
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subf. r29, r27, r29
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dcbf r29, r28
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sync
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icbi r29, r28
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bge kcRTASDispatch_0x190
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sync
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isync
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lwz r8, 0x0000(r6)
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lwz r11, 0x00a4(r6)
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mr r7, r8
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andi. r8, r11, 0x900
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lwz r8, 0x0004(r6)
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lwz r13, 0x00dc(r6)
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stw r8, EWA.Enables(r1)
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lwz r8, 0x00d4(r6)
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lwz r12, 0x00ec(r6)
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mtxer r8
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lwz r8, 0x00f4(r6)
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lwz r10, 0x00fc(r6)
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mtctr r8
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bnel major_0x03e18_0x8
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lwz r8, 0x010c(r6)
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stw r8, 0x0004(r1)
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lwz r2, 0x0114(r6)
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lwz r3, 0x011c(r6)
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lwz r4, 0x0124(r6)
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lwz r8, 0x0134(r6)
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lwz r5, 0x012c(r6)
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stw r8, 0x0018(r1)
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lwz r14, 0x0174(r6)
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lwz r15, 0x017c(r6)
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lwz r16, 0x0184(r6)
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lwz r17, 0x018c(r6)
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lwz r18, 0x0194(r6)
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lwz r19, 0x019c(r6)
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lwz r20, 0x01a4(r6)
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lwz r21, 0x01ac(r6)
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lwz r22, 0x01b4(r6)
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lwz r23, 0x01bc(r6)
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lwz r24, 0x01c4(r6)
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lwz r25, 0x01cc(r6)
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lwz r26, 0x01d4(r6)
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lwz r27, 0x01dc(r6)
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lwz r28, 0x01e4(r6)
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lwz r29, 0x01ec(r6)
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lwz r30, 0x01f4(r6)
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lwz r31, 0x01fc(r6)
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_AssertAndRelease PSA.RTASLock, scratch=r8
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li r3, 0x00
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b IntReturn
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rtas_make_actual_call
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mtctr r9
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bctr
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