mirror of https://github.com/elliotnunn/wedge.git
85 lines
2.3 KiB
ArmAsm
85 lines
2.3 KiB
ArmAsm
; MakeFunction sets up everything you need to make an assembly function
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; callable from C and debuggable with a symbolic debugger. It does the following:
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; - export the function's transition vector
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; - export the function name
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; - create a toc entry for the function's transition vector
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; - create the transition vector, which must contain
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; - the function entry point (the name of the function)
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; - the TOC anchor (the predefined variable TOC[tc0])
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; - tell PPCAsm to create a function entry point symbol for symbolic debuggers
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; - create a csect for the function (one csect per function lets the
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; linker do dead code stripping, resulting in smaller executables)
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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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linkageArea: set 24 ; constant comes from the PowerPC Runtime Architecture Document
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CalleesParams: set 32 ; always leave space for GPR's 3-10
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CalleesLocalVars: set 0 ; NKxprintf doesn't have any
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numGPRs: set 0 ; num volitile GPR's (GPR's 13-31) used by NKxprintf
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numFPRs: set 0 ; num volitile FPR's (FPR's 14-31) used by NKxprintf
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spaceToSave: set linkageArea + CalleesParams + CalleesLocalVars + 4*numGPRs + 8*numFPRs
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; declare the C function DisplayAlert as external
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import .DisplayAlert
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import gHelloString ; global variable from C program
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import gGoodbyeString ; global variable from C program
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toc
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tc gHelloString[TC], gHelloString
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tc gGoodbyeString[TC], gGoodbyeString
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; Call the MakeFunction macro, defined in MakeFunction.s to begin the function
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MakeFunction NKxprintf
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li r0, 96
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sc
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blr
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MakeFunction NKLocateInfoRecord ; Lifted shamelessly from MPLibrary
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stw r4,0x001C(SP)
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stw r5,0x0020(SP)
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stw r6,0x0024(SP)
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li r0,107
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sc
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cmpwi r3,0
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bnelr
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lwz r7,0x001C(SP)
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lwz r8,0x0020(SP)
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lwz r9,0x0024(SP)
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cmplwi cr5,r7,0x0000
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cmplwi cr6,r8,0x0000
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cmplwi cr7,r9,0x0000
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beq cr5,$+0x0008 ; 0x00008440
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stw r4,0x0000(r7)
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beq cr6,$+0x0008 ; 0x00008448
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stw r5,0x0000(r8)
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beq cr7,$+0x0008 ; 0x00008450
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stw r6,0x0000(r9)
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blr
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MakeFunction NKKernelDebuggerCmd
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li r0, 200
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sc
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blr
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