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// picoChip ASM file

//

//   Support for 16-bit unsigned division/modulus.

//

//   Copyright (C) 2003, 2004, 2005, 2008, 2009  Free Software Foundation, Inc.

//   Contributed by Picochip 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

//   .

.section .text

.global __udivmodhi4

__udivmodhi4:

_picoMark_FUNCTION_BEGIN=

// picoChip Function Prologue : &__udivmodhi4 = 6 bytes

        // 16-bit unsigned division. The divstep function is only capable of

        // handling 15-bit division (plus a sign to give 16-bits). It is not

        // capable of handling unsigned division directly. Instead, take

        // advantage of the special property that

        // ((divisor / 2) / dividend) * 2 will be almost good enough. The

        // error in the result is only 0 or 1, and this can be easily

        // tested and corrected. A full description of the algorithm can

        // be found in `Hacker's Delight', by Henry Warren, page 146.

        // Input:

        //      r0 - dividend

        //      r1 - divisor

        // Output:

        //      r0 - quotient

        //      r1 - remainder

        // Note that the lr, and original inputs are speculatively saved. They

        // will only be restored if the 15-bit division function is called.

        sub.0 r1,0,r15 \ stl r[0:1],(fp)-1

        bge divisorIs15bit

=->     sub.0 r0,r1,r2 \ stw lr,(fp)-3

        // The divisor is >= 2^15.

        bhs quotientIs1

        // The dividend < divisor. The quotient is thus 0, and the

        // remainder is the dividend.

        copy.0 r0,r1 \ jr (lr)

=->     copy.0 0,r0

quotientIs1:

        // The dividend >= divisor. The quotient is thus 1, and the

        // remainder can be computed directly by subtraction (i.e., the

        // result of the comparison already performed to branch here).

        jr (lr) \ copy.0 r2,r1

=->     copy.0 1,r0

divisorIs15bit:

        // The divisor is < 2^15.

        // Divide the original dividend by 2, and call the 15-bit division.

        // Note that the original dividend is stored in r5, which is

        // known to be unused by the called function, so that

        // a memory stall isn't introduced immediately after the

        // function returns, to reload this value from memory.

        jl (&__divmod15) \ copy.0 r0,r5  // fn_call &__divmod15

=->     lsr.0 r0,1,r0

        // Compute the new quotient and remainder by multiplying them by 2.

        // The remainder will be 1 out, if the original dividend was odd.

        and.0 r5,1,r5 \ ldl (fp)-1,r[2:3]

        add.0 [lsl r1,1],r5,r1 \ lsl.1 r0,1,r0

        // The error in the quotient is 0 or 1. The error can be determined

        // by comparing the remainder to the original divisor. If the

        // remainder is bigger, then an error of 1 has been introduced.

        sub.0 r1,r3,r15 \ ldw (fp)-3,lr

        blo noCompensation

=->     nop

        add.0 r0,1,r0 \ sub.1 r1,r3,r1

noCompensation:

        jr (lr)

_picoMark_FUNCTION_END=

// picoChip Function Epilogue : udivmodhi4

//============================================================================

// 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 0x6    // <-- 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#68# 16#69# 16#34# 16#0# // Function name `_udivmodhi4'

.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