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// picoChip ASM file
//
//   Support for 32-bit signed 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 __divmodsi4
__divmodsi4:
_picoMark_FUNCTION_BEGIN=
// picoChip Function Prologue : &__divmodsi4 = 8 bytes

        // Note: optimising for size is preferred over optimising for speed.

        // Note: the frame is setup throughout the following instructions,
        // and is complete at the point the udivmodsi4 function is called.      

        // Note that R9 is encoded with a pattern which indicates
        // whether the remainder and quotient should be negated on
        // completion. The MSB is set to the sign of the dividend
        // (i.e., the sign of the remainder), while the LSB encodes
        // the XOR of the two input's signs (i.e., the sign of the
        // quotient.
        
        // If dividend is negative, invert the dividend and flag.
        ASR.0 r1,15,r4
        BEQ dividendNotNegative
=->     STL R[9:8],(FP)-2

        // Dividend is negative - negate dividend.
        SUB.0 0,R0,R0
        SUBB.0 0,R1,R1

dividendNotNegative:
                        
        // If divisor is negative, invert the divisor.
        AND.0 [lsr r3,15],1,r5
        SUB.0 R3,0, r15
        BGE divisorNotNegative
=->     XOR.0 r4,r5,r9

        // Divisor is negative - negate divisor.
        SUB.0 0,R2,R2
        SUBB.0 0,R3,R3

divisorNotNegative:
        
        STL R[13:12],(FP)-1 \ JL (&__udivmodsi4)
=->     SUB.0 FP,8,FP  // udivmodsi expects the frame to be valid still.
        
        // The LSB of R9 indicates whether the quotient should be negated.
        AND.0 r9,1,r15
        BEQ skipQuotientNegation
=->     LDL (FP)1,R[13:12]      // Convenient point to restore link/fp
        
        SUB.0 0,R4,R4
        SUBB.0 0,R5,R5  

skipQuotientNegation:           

        // The MSB of R9 indicates whether the remainder should be negated.
        ASR.0 R9,15,r15
        BEQ epilogue

        SUB.0 0,R6,R6
        SUBB.0 0,R7,R7

epilogue:       

        JR (R12)
=->     LDL (FP)-2,R[9:8]

_picoMark_FUNCTION_END=
// picoChip Function Epilogue : __divmodsi4

//============================================================================
// 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 0x8    // <-- 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#64# 16#69# 16#76# 16#6d# 16#6f# 16#64# 16#73# 16#69# 16#34# 16#0# // Function name `_divmodsi4'
.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