319 lines
9.4 KiB
ArmAsm
319 lines
9.4 KiB
ArmAsm
// picoChip ASM file
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//
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// Support for 32-bit unsigned division/modulus.
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//
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// Copyright (C) 2003, 2004, 2005, 2008, 2009 Free Software Foundation, Inc.
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// Contributed by Picochip Ltd.
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// Maintained by Daniel Towner (daniel.towner@picochip.com)
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//
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// This file is free software; you can redistribute it and/or modify it
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// under the terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option) any
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// later version.
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//
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// This file is distributed in the hope that it will be useful, but
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// WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// General Public License for more details.
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//
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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//
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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.section .text
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.align 8
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.global __udivmodsi4
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__udivmodsi4:
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_picoMark_FUNCTION_BEGIN=
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// picoChip Function Prologue : &__udivmodsi4 = 24 bytes
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// Schedule the register saves alongside the special cases, so that
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// if the special cases fail, the registers will have already
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// been stored onto the stack.
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SUB.0 R3,R1,r15 \ STL R[13:12],(FP)-1
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BHS skipCommonCase \ STL R[9:8],(FP)-4
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=-> SUB.0 R2,1,r15 \ STL R[11:10],(FP)-3
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_L2:
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// Flags set above, and in _L2 caller.
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BNE restOfCode
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=-> SUB.0 R3,0,r15
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BNE restOfCode
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=-> COPY.0 R0,R4 \ COPY.1 R1,R5
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JR (R12) // Return to caller
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=-> COPY.0 0,R6 \ COPY.1 0,R7
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// Never reach here
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skipCommonCase:
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SUB.0 R3,R1,r15
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BNE _L3 // (Reversed branch)
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=-> SUB.0 R2,R0,r15 // Must be set in delay slot, so ready by _L9
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_L9:
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BLO _L2 // (Reversed branch)
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=-> SUB.0 R2,1,r15
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_L3:
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SUB.0 R2,R0,r15
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BEQ _L10 // (Reversed branch)
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=-> SUB.0 R1,R3,r15 // Set flags for branch at _L10
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_L4:
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// greater than
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COPY.0 0,R4 \ COPY.1 0,R5 \ JR (R12) // Return to caller
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=-> COPY.0 R0,R6 \ COPY.1 R1,R7
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// Doesn't reach here.
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_L10:
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// Flags set in _L10 call delay slot.
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BNE _L4
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=-> COPY.0 1,R4 \ COPY.1 0,R5
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JR (R12) // Return to caller
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=-> COPY.0 0,R6 \ COPY.1 0,R7
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restOfCode:
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// Prologue
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// Register saves scheduled alongside special cases above.
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ADD.0 FP,-20,FP \ STW R14,(FP)-4
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// The following can be scheduled together.
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// dividend in R[9:8] (from R[1:0])
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// divisor in R[7:6] (from R[3:2])
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// R14 := clzsi2 (dividend)
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// R0 := clzsi2 (divisor)
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JL (&__clzsi2) \ COPY.0 R0,R8 \ COPY.1 R1,R9
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=-> COPY.0 R2,R6 \ COPY.1 R3,R7
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COPY.0 R0,R14 \ JL (&__clzsi2)
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=-> COPY.0 R6,R0 \ COPY.1 R7,R1
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// R14 := R0 - R14
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SUB.0 R0,R14,R14
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ADD.0 R14,1,R0 // R0 := R14 + 1 (HI)
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// R[11:10] = R[7,6] << R14
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SUB.0 15,R14,r15
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LSL.0 R6,R14,R11 \ BLT setupDivstepLoop
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=-> SUB.0 0,R14,R4 \ COPY.1 0,R10
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// Zero shift is a special case. Shifting by zero within a 16-bit
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// source object is fine, but don't execute the OR of the right-shift
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// into the final result.
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LSL.0 R7,R14,R11 \ BEQ setupDivstepLoop
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=-> LSL.0 R6,R14,R10
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LSR.0 R6,R4,R4
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OR.0 R11,R4,R11
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setupDivstepLoop:
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// R[5:4] := R[9:8] (SI)
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COPY.0 R8,R4 \ COPY.1 R9,R5
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COPY.0 0,R6 \ COPY.1 R0,R8
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// Store original value of loopCount for use after the loop.
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// The Subtraction is handled in the tail of the loop iteration
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// after this point.
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SUB.0 R4,R10,R0 \ COPY.1 R8,R14
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// workingResult in R4,5,6
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// temps in r0,1,2 and r7
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// alignedDivisor in R10,11
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// loopCount in r8
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// r3, r9 scratch, used for renaming.
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loopStart:
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// R0 := R4 - zeroExtend (R10) - only need 33-bits (i.e., 48-bits)
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SUBB.0 R5,R11,R1 \ LSR.1 R0,15,R3
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SUBB.0 R6,0,R2 \ LSR.1 R1,15,R6
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// if (carry) goto shiftOnly
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SUB.0 R8,1,R8 \ BNE shiftOnly
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=-> LSR.0 R4,15,R7 \ LSL.1 R1,1,R9
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OR.0 [LSL R0,1],1,R4 \ BNE loopStart
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=-> SUB.0 R4,R10,R0 \ OR.1 R9,R3,R5
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BRA loopEnd
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shiftOnly:
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OR.0 [LSL R5,1],R7,R5 \ BNE loopStart \ LSR.1 R5,15,R6
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=-> SUB.0 [LSL R4,1],R10,R0 \LSL.1 R4,1,R4
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// End of loop
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loopEnd:
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// Schedule the computation of the upper word after shifting
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// alongside the decision over whether to branch, and the register
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// restores.
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// R10 is filled with a useful constant.
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SUB.0 15,r14,r15 \ LDL (FP)4,R[13:12]
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SUB.1 0,R14,R1 // Don't set flags!
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LSL.0 R6,R1,R3 \ LDL (FP)-4,R[9:8]
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BLT remainderHasMoreThan16Bits \ LSR.0 R5,R14,R7 \ COPY.1 -1,R10
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=-> LSL.0 R5,R1,R2 \ OR.1 R7,R3,R3
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LSR.0 R4,R14,R3 \ COPY.1 R3,R7
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BRA epilogue \ LSR.0 -1,R1,R0 \ COPY.1 0,R5
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=-> OR.0 R3,R2,R6 \ AND.1 R0,R4,R4
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remainderHasMoreThan16Bits:
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LSL.0 R10,R14,R1 \ COPY.1 R3,R6
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XOR.0 R10,R1,R1 \ COPY.1 0,R7
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AND.0 R1,R5,R5
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epilogue:
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JR (R12) \ LDW (FP)-4,R14
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=-> LDL (FP)-3,R[11:10]
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_picoMark_FUNCTION_END=
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// picoChip Function Epilogue : udivmodsi4
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//============================================================================
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// All DWARF information between this marker, and the END OF DWARF
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// marker should be included in the source file. Search for
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// FUNCTION_STACK_SIZE_GOES_HERE and FUNCTION NAME GOES HERE, and
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// provide the relevant information. Add markers called
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// _picoMark_FUNCTION_BEGIN and _picoMark_FUNCTION_END around the
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// function in question.
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//============================================================================
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//============================================================================
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// Frame information.
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//============================================================================
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.section .debug_frame
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_picoMark_DebugFrame=
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// Common CIE header.
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.unalignedInitLong _picoMark_CieEnd-_picoMark_CieBegin
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_picoMark_CieBegin=
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.unalignedInitLong 0xffffffff
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.initByte 0x1 // CIE Version
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.ascii 16#0# // CIE Augmentation
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.uleb128 0x1 // CIE Code Alignment Factor
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.sleb128 2 // CIE Data Alignment Factor
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.initByte 0xc // CIE RA Column
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.initByte 0xc // DW_CFA_def_cfa
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.uleb128 0xd
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.uleb128 0x0
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.align 2
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_picoMark_CieEnd=
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// FDE
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_picoMark_LSFDE0I900821033007563=
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.unalignedInitLong _picoMark_FdeEnd-_picoMark_FdeBegin
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_picoMark_FdeBegin=
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.unalignedInitLong _picoMark_DebugFrame // FDE CIE offset
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.unalignedInitWord _picoMark_FUNCTION_BEGIN // FDE initial location
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.unalignedInitWord _picoMark_FUNCTION_END-_picoMark_FUNCTION_BEGIN
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.initByte 0xe // DW_CFA_def_cfa_offset
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.uleb128 0x18 // <-- FUNCTION_STACK_SIZE_GOES_HERE
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.initByte 0x4 // DW_CFA_advance_loc4
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.unalignedInitLong _picoMark_FUNCTION_END-_picoMark_FUNCTION_BEGIN
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.initByte 0xe // DW_CFA_def_cfa_offset
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.uleb128 0x0
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.align 2
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_picoMark_FdeEnd=
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//============================================================================
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// Abbrevation information.
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//============================================================================
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.section .debug_abbrev
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_picoMark_ABBREVIATIONS=
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.section .debug_abbrev
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.uleb128 0x1 // (abbrev code)
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.uleb128 0x11 // (TAG: DW_TAG_compile_unit)
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.initByte 0x1 // DW_children_yes
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.uleb128 0x10 // (DW_AT_stmt_list)
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.uleb128 0x6 // (DW_FORM_data4)
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.uleb128 0x12 // (DW_AT_high_pc)
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.uleb128 0x1 // (DW_FORM_addr)
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.uleb128 0x11 // (DW_AT_low_pc)
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.uleb128 0x1 // (DW_FORM_addr)
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.uleb128 0x25 // (DW_AT_producer)
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.uleb128 0x8 // (DW_FORM_string)
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.uleb128 0x13 // (DW_AT_language)
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.uleb128 0x5 // (DW_FORM_data2)
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.uleb128 0x3 // (DW_AT_name)
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.uleb128 0x8 // (DW_FORM_string)
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.initByte 0x0
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.initByte 0x0
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.uleb128 0x2 ;# (abbrev code)
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.uleb128 0x2e ;# (TAG: DW_TAG_subprogram)
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.initByte 0x0 ;# DW_children_no
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.uleb128 0x3 ;# (DW_AT_name)
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.uleb128 0x8 ;# (DW_FORM_string)
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.uleb128 0x11 ;# (DW_AT_low_pc)
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.uleb128 0x1 ;# (DW_FORM_addr)
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.uleb128 0x12 ;# (DW_AT_high_pc)
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.uleb128 0x1 ;# (DW_FORM_addr)
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.initByte 0x0
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.initByte 0x0
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.initByte 0x0
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//============================================================================
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// Line information. DwarfLib requires this to be present, but it can
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// be empty.
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//============================================================================
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.section .debug_line
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_picoMark_LINES=
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//============================================================================
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// Debug Information
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//============================================================================
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.section .debug_info
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//Fixed header.
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.unalignedInitLong _picoMark_DEBUG_INFO_END-_picoMark_DEBUG_INFO_BEGIN
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_picoMark_DEBUG_INFO_BEGIN=
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.unalignedInitWord 0x2
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.unalignedInitLong _picoMark_ABBREVIATIONS
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.initByte 0x2
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// Compile unit information.
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.uleb128 0x1 // (DIE 0xb) DW_TAG_compile_unit)
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.unalignedInitLong _picoMark_LINES
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.unalignedInitWord _picoMark_FUNCTION_END
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.unalignedInitWord _picoMark_FUNCTION_BEGIN
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// Producer is `picoChip'
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.ascii 16#70# 16#69# 16#63# 16#6f# 16#43# 16#68# 16#69# 16#70# 16#00#
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.unalignedInitWord 0xcafe // ASM language
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.ascii 16#0# // Name. DwarfLib expects this to be present.
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.uleb128 0x2 ;# (DIE DW_TAG_subprogram)
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// FUNCTION NAME GOES HERE. Use `echo name | od -t x1' to get the hex. Each hex
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// digit is specified using the format 16#XX#
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.ascii 16#5f# 16#75# 16#64# 16#69# 16#76# 16#6d# 16#6f# 16#64# 16#73# 16#69# 16#34# 16#0# // Function name `_udivmodsi4'
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.unalignedInitWord _picoMark_FUNCTION_BEGIN // DW_AT_low_pc
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.unalignedInitWord _picoMark_FUNCTION_END // DW_AT_high_pc
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.initByte 0x0 // end of compile unit children.
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_picoMark_DEBUG_INFO_END=
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//============================================================================
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// END OF DWARF
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//============================================================================
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.section .endFile
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// End of picoChip ASM file
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