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https://github.com/elliotnunn/wedge.git
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115 lines
1.6 KiB
ArmAsm
115 lines
1.6 KiB
ArmAsm
PA_ROM equ 0x00c00000
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Me equ 0x310000
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Middle equ 0x320000
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NK equ 0x340000
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Magic equ 'Wdg_'
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MACRO
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MakeFunction &fnName
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EXPORT &fnName[DS]
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EXPORT .&fnName[PR]
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TC &fnName[TC], &fnName[DS]
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CSECT &fnName[DS]
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DC.L .&fnName[PR]
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DC.L TOC[tc0]
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CSECT .&fnName[PR]
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FUNCTION .&fnName[PR]
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ENDM
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MACRO
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lisori ®, &val
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lis ®, ((&val) >> 16) & 0xffff
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ori ®, ®, (&val) & 0xffff
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ENDM
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MakeFunction __start
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import .wedge
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; Pointers in r20, scratch values in r0
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; Need to reference MagicSentinel so that it gets put before the string table
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; (There is probably a better way)
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b * + 8
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dc.l MagicSentinel{RO}
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; Initial debug log
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lisori r20, PA_ROM + Middle
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lisori r0, 'WgLg'
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stw r0, -8(r20)
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; Search for the string table (tested, works)
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bl * + 4
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mflr r20 ; start here
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@a lwzu r0, 4(r20) ; find the sentinel
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xoris r0, r0, Magic >> 16
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cmplwi r0, Magic & 0xffff
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bne @a
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@b lwzu r0, 4(r20) ; skip the csect padding
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cmpwi r0, 0
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beq @b
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; Set RTOC and save string table ptr at -4(RTOC)
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lisori RTOC, PA_ROM + Middle - 64
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stw r20, -4(RTOC)
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; Get a stack, just below the waistline
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lisori SP, PA_ROM + Middle - 128
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; Go
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b .wedge
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MakeFunction NanoKernelJump
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lisori r0, PA_ROM + NK
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mtlr r0
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blr
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MakeFunction asm_putc
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; Just a stub/test function for now
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lisori r6, PA_ROM + Middle
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lwz r5, -4(r6)
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; lbz r4, 0(r3)
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stbx r3, r5, r6
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addi r5, r5, 1
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stw r5, -4(r6)
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li r3, 0
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blr
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; Insert a sentinel value just before the C string table
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; (Requires PPCLink -codeorder source -roistext on)
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csect MagicSentinel[RO]
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dc.l Magic
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