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// picoChip ASM file
//
//   Support for 32-bit unsigned division/modulus.
//
//   Copyright (C) 2003, 2004, 2005, 2008, 2009  Free Software Foundation, Inc.
//   Contributed by picoChip Designs Ltd.
//   Maintained by Daniel Towner (daniel.towner@picochip.com)
//
//   This file is free software; you can redistribute it and/or modify it
//   under the terms of the GNU General Public License as published by the
//   Free Software Foundation; either version 3, or (at your option) any
//   later version.
//
//   This file is distributed in the hope that it will be useful, but
//   WITHOUT ANY WARRANTY; without even the implied warranty of
//   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
//   General Public License for more details.
//
//   Under Section 7 of GPL version 3, you are granted additional
//   permissions described in the GCC Runtime Library Exception, version
//   3.1, as published by the Free Software Foundation.
//
//   You should have received a copy of the GNU General Public License and
//   a copy of the GCC Runtime Library Exception along with this program;
//   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
//   <http://www.gnu.org/licenses/>.
        
.section .text

.align 8
.global __udivmodsi4
__udivmodsi4:
_picoMark_FUNCTION_BEGIN=
// picoChip Function Prologue : &__udivmodsi4 = 24 bytes
        
        // Schedule the register saves alongside the special cases, so that
        // if the special cases fail, the registers will have already
        // been stored onto the stack.
        SUB.0 R3,R1,r15 \ STL R[13:12],(FP)-1
        BHS skipCommonCase \ STL R[9:8],(FP)-4
=->     SUB.0 R2,1,r15 \ STL R[11:10],(FP)-3
        
_L2:
        // Flags set above, and in _L2 caller.
        BNE restOfCode
=->     SUB.0 R3,0,r15
        BNE restOfCode 
=->     COPY.0 R0,R4 \ COPY.1 R1,R5
        JR (R12)        // Return to caller
=->     COPY.0 0,R6 \ COPY.1 0,R7
        // Never reach here

skipCommonCase:
        SUB.0 R3,R1,r15
        BNE _L3 // (Reversed branch) 
=->     SUB.0 R2,R0,r15 // Must be set in delay slot, so ready by _L9

_L9:
        BLO _L2 // (Reversed branch)
=->     SUB.0 R2,1,r15
        
_L3:
        SUB.0 R2,R0,r15
        BEQ _L10        // (Reversed branch)
=->     SUB.0 R1,R3,r15 // Set flags for branch at _L10 
        
_L4:
        // greater than
        COPY.0 0,R4 \ COPY.1 0,R5 \ JR (R12)    // Return to caller
=->     COPY.0 R0,R6 \ COPY.1 R1,R7
        // Doesn't reach here.
                
_L10:
        // Flags set in _L10 call delay slot.
        BNE _L4 
=->     COPY.0 1,R4 \ COPY.1 0,R5
        JR (R12)        // Return to caller
=->     COPY.0 0,R6 \ COPY.1 0,R7

restOfCode:     

// Prologue
        
        // Register saves scheduled alongside special cases above.
        ADD.0 FP,-20,FP \ STW R14,(FP)-4

        // The following can be scheduled together.
        // dividend in R[9:8] (from R[1:0])
        // divisor in R[7:6] (from R[3:2])
        // R14 := clzsi2 (dividend)     
        // R0 := clzsi2 (divisor)
        JL (&__clzsi2) \ COPY.0 R0,R8 \ COPY.1 R1,R9
=->     COPY.0 R2,R6 \ COPY.1 R3,R7
        COPY.0 R0,R14 \ JL (&__clzsi2)
=->     COPY.0 R6,R0 \ COPY.1 R7,R1

        // R14 := R0 - R14
        SUB.0 R0,R14,R14

        ADD.0 R14,1,R0  // R0 := R14 + 1 (HI)
        
        // R[11:10] = R[7,6] << R14
        SUB.0 15,R14,r15
        LSL.0 R6,R14,R11 \ BLT setupDivstepLoop
=->     SUB.0 0,R14,R4 \ COPY.1 0,R10

        // Zero shift is a special case. Shifting by zero within a 16-bit
        // source object is fine, but don't execute the OR of the right-shift
        // into the final result.
        LSL.0 R7,R14,R11 \ BEQ setupDivstepLoop
=->     LSL.0 R6,R14,R10
        
        LSR.0 R6,R4,R4
        OR.0 R11,R4,R11
        
setupDivstepLoop:

        // R[5:4] := R[9:8] (SI)
        COPY.0 R8,R4 \ COPY.1 R9,R5
        COPY.0 0,R6 \ COPY.1 R0,R8

        // Store original value of loopCount for use after the loop.
        // The Subtraction is handled in the tail of the loop iteration
        // after this point.
        SUB.0 R4,R10,R0 \ COPY.1 R8,R14
        
        // workingResult in R4,5,6
        // temps in r0,1,2 and r7
        // alignedDivisor in R10,11
        // loopCount in r8
        // r3, r9 scratch, used for renaming.
        
loopStart:      
        // R0 := R4 - zeroExtend (R10) - only need 33-bits (i.e., 48-bits)
        SUBB.0 R5,R11,R1 \ LSR.1 R0,15,R3
        SUBB.0 R6,0,R2 \ LSR.1 R1,15,R6

        // if (carry) goto shiftOnly
        SUB.0 R8,1,R8 \ BNE shiftOnly
=->     LSR.0 R4,15,R7 \ LSL.1 R1,1,R9
        
        OR.0 [LSL R0,1],1,R4 \ BNE loopStart
=->     SUB.0 R4,R10,R0 \ OR.1 R9,R3,R5
        
        BRA loopEnd
        
shiftOnly:      

        OR.0 [LSL R5,1],R7,R5 \ BNE loopStart \ LSR.1 R5,15,R6
=->     SUB.0 [LSL R4,1],R10,R0 \LSL.1 R4,1,R4
        
// End of loop
loopEnd:

        // Schedule the computation of the upper word after shifting
        // alongside the decision over whether to branch, and the register
        // restores.
        // R10 is filled with a useful constant.
        SUB.0 15,r14,r15 \ LDL (FP)4,R[13:12]
        SUB.1 0,R14,R1 // Don't set flags!
        LSL.0 R6,R1,R3 \ LDL (FP)-4,R[9:8]

        BLT remainderHasMoreThan16Bits \ LSR.0 R5,R14,R7 \ COPY.1 -1,R10
=->     LSL.0 R5,R1,R2 \ OR.1 R7,R3,R3

        LSR.0 R4,R14,R3 \ COPY.1 R3,R7
        BRA epilogue \ LSR.0 -1,R1,R0 \ COPY.1 0,R5
=->     OR.0 R3,R2,R6 \ AND.1 R0,R4,R4
        
remainderHasMoreThan16Bits:     

        LSL.0 R10,R14,R1 \ COPY.1 R3,R6
        XOR.0 R10,R1,R1 \ COPY.1 0,R7
        AND.0 R1,R5,R5

epilogue:
        
        JR (R12) \ LDW (FP)-4,R14
=->     LDL (FP)-3,R[11:10]

_picoMark_FUNCTION_END=
        
// picoChip Function Epilogue : udivmodsi4

//============================================================================
// All DWARF information between this marker, and the END OF DWARF
// marker should be included in the source file. Search for
// FUNCTION_STACK_SIZE_GOES_HERE and FUNCTION NAME GOES HERE, and
// provide the relevent information. Add markers called
// _picoMark_FUNCTION_BEGIN and _picoMark_FUNCTION_END around the
// function in question.
//============================================================================

//============================================================================
// Frame information. 
//============================================================================

.section .debug_frame
_picoMark_DebugFrame=

// Common CIE header.
.unalignedInitLong _picoMark_CieEnd-_picoMark_CieBegin
_picoMark_CieBegin=
.unalignedInitLong 0xffffffff
.initByte 0x1   // CIE Version
.ascii 16#0#    // CIE Augmentation
.uleb128 0x1    // CIE Code Alignment Factor
.sleb128 2      // CIE Data Alignment Factor
.initByte 0xc   // CIE RA Column
.initByte 0xc   // DW_CFA_def_cfa
.uleb128 0xd
.uleb128 0x0
.align 2
_picoMark_CieEnd=

// FDE 
_picoMark_LSFDE0I900821033007563=
.unalignedInitLong _picoMark_FdeEnd-_picoMark_FdeBegin
_picoMark_FdeBegin=
.unalignedInitLong _picoMark_DebugFrame // FDE CIE offset
.unalignedInitWord _picoMark_FUNCTION_BEGIN     // FDE initial location
.unalignedInitWord _picoMark_FUNCTION_END-_picoMark_FUNCTION_BEGIN
.initByte 0xe   // DW_CFA_def_cfa_offset
.uleb128 0x18   // <-- FUNCTION_STACK_SIZE_GOES_HERE
.initByte 0x4   // DW_CFA_advance_loc4
.unalignedInitLong _picoMark_FUNCTION_END-_picoMark_FUNCTION_BEGIN
.initByte 0xe   // DW_CFA_def_cfa_offset
.uleb128 0x0
.align 2
_picoMark_FdeEnd=

//============================================================================
// Abbrevation information.
//============================================================================

.section .debug_abbrev
_picoMark_ABBREVIATIONS=

.section .debug_abbrev
        .uleb128 0x1    // (abbrev code)
        .uleb128 0x11   // (TAG: DW_TAG_compile_unit)
        .initByte 0x1   // DW_children_yes
        .uleb128 0x10   // (DW_AT_stmt_list)
        .uleb128 0x6    // (DW_FORM_data4)
        .uleb128 0x12   // (DW_AT_high_pc)
        .uleb128 0x1    // (DW_FORM_addr)
        .uleb128 0x11   // (DW_AT_low_pc)
        .uleb128 0x1    // (DW_FORM_addr)
        .uleb128 0x25   // (DW_AT_producer)
        .uleb128 0x8    // (DW_FORM_string)
        .uleb128 0x13   // (DW_AT_language)
        .uleb128 0x5    // (DW_FORM_data2)
        .uleb128 0x3    // (DW_AT_name)
        .uleb128 0x8    // (DW_FORM_string)
.initByte 0x0
.initByte 0x0

        .uleb128 0x2    ;# (abbrev code)
        .uleb128 0x2e   ;# (TAG: DW_TAG_subprogram)
.initByte 0x0   ;# DW_children_no
        .uleb128 0x3    ;# (DW_AT_name)
        .uleb128 0x8    ;# (DW_FORM_string)
        .uleb128 0x11   ;# (DW_AT_low_pc)
        .uleb128 0x1    ;# (DW_FORM_addr)
        .uleb128 0x12   ;# (DW_AT_high_pc)
        .uleb128 0x1    ;# (DW_FORM_addr)
.initByte 0x0
.initByte 0x0

.initByte 0x0

//============================================================================
// Line information. DwarfLib requires this to be present, but it can
// be empty.
//============================================================================

.section .debug_line
_picoMark_LINES=

//============================================================================
// Debug Information
//============================================================================
.section .debug_info

//Fixed header.
.unalignedInitLong _picoMark_DEBUG_INFO_END-_picoMark_DEBUG_INFO_BEGIN
_picoMark_DEBUG_INFO_BEGIN=
.unalignedInitWord 0x2
.unalignedInitLong _picoMark_ABBREVIATIONS
.initByte 0x2

// Compile unit information.
.uleb128 0x1    // (DIE 0xb) DW_TAG_compile_unit)
.unalignedInitLong _picoMark_LINES
.unalignedInitWord _picoMark_FUNCTION_END
.unalignedInitWord _picoMark_FUNCTION_BEGIN
// Producer is `picoChip'
.ascii 16#70# 16#69# 16#63# 16#6f# 16#43# 16#68# 16#69# 16#70# 16#00#
.unalignedInitWord 0xcafe // ASM language
.ascii 16#0# // Name. DwarfLib expects this to be present.

.uleb128 0x2    ;# (DIE DW_TAG_subprogram)

// FUNCTION NAME GOES HERE. Use `echo name | od -t x1' to get the hex. Each hex
// digit is specified using the format 16#XX#
.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'
.unalignedInitWord _picoMark_FUNCTION_BEGIN     // DW_AT_low_pc
.unalignedInitWord _picoMark_FUNCTION_END       // DW_AT_high_pc

.initByte 0x0   // end of compile unit children.

_picoMark_DEBUG_INFO_END=

//============================================================================
// END OF DWARF
//============================================================================
.section .endFile
// End of picoChip ASM file