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// picoChip ASM file

//

//   Support for 16-bit signed 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

.align 8

.global __divmodhi4

__divmodhi4:

_picoMark_FUNCTION_BEGIN=

// picoChip Function Prologue : &__divmodhi4 = 4 bytes

        // 16-bit signed division. Most of the special cases are dealt

        // with by the 15-bit signed division library (e.g., division by

        // zero, division by 1, and so on). This wrapper simply inverts

        // any negative inputs, calls the 15-bit library, and flips any

        // results as necessary.  The

        // only special cases to be handled here are where either the

        // divisor or the dividend are the maximum negative values.

        // Encode r5 with a bit pattern which indicates whether the

        // outputs of the division must be negated. The MSB will be set

        // to the sign of the dividend (which controls the remainder's

        // sign), while the LSB will store the XOR of the two signs,

        // which indicates the quotient's sign. R5 is not modified by the

        // 15-bit divmod routine.

        sub.0 r1,16#8000#,r15 \ asr.1 r0,15,r4

        beq divisorIsLargestNegative \ lsr.0 r1,15,r3

=->     sub.0 r0,16#8000#,r15 \ xor.1 r3,r4,r5

        // Handle least negative dividend with a special case. Note that the

        // absolute value of the divisor is also computed here.

        add.0 [asr r1,15],r1,r3 \ beq dividendIsLargestNegative

=->     xor.0 [asr r1,15],r3,r1 \ stw lr,(fp)-1

        // Compute the absolute value of the dividend, and call the main

        // divide routine.

        add.0 r4,r0,r2 \ jl (&__divmod15)  // fn_call &__divmod15

=->     xor.0 r4,r2,r0

handleNegatedResults:

        // Speculatively store the negation of the results.

        sub.0 0,r0,r2 \ sub.1 0,r1,r3

        // Does the quotient need negating? The LSB indicates this.

        and.0 r5,1,r15 \ ldw (fp)-1,lr

        copyne r2,r0

        asr.0 r5,15,r15 \ jr (lr)

=->     copyne r3,r1

dividendIsLargestNegative:

        // Divide the constant -32768. Use the Hacker's Delight

        // algorithm (i.e., ((dividend / 2) / divisor) * 2) gives

        // approximate answer). This code is a special case, so no

        // great effort is made to make it fast, only to make it

        // small.

        lsr.0 r0,1,r0 \ jl (&__divmod15)  // fn_call &__divmod15

=->     stw r1,(fp)-2

        // Load the original divisor, and compute the new quotient and

        // remainder.

        lsl.0 r0,1,r0 \ ldw (fp)-2,r3

        lsl.0 r1,1,r1 // Fill stall slot

        // 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,

        // which must be fixed.

        sub.0 r1,r3,r15

        blo noCompensationForError

=->     nop

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

noCompensationForError:

        bra handleNegatedResults

=->     nop

divisorIsLargestNegative:

        // The flags indicate whether the dividend is also the maximum negative

        copy.0 r0,r1 \ copy.1 0,r0

        copyeq r0,r1 \ jr (lr)

=->     copyeq 1,r0

_picoMark_FUNCTION_END=

// picoChip Function Epilogue : __divmodhi4

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

// 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 0x4    // <-- 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#68# 16#69# 16#34# 16#0# // Function name `_divmodhi4'

.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