208 lines
5.2 KiB
ArmAsm
208 lines
5.2 KiB
ArmAsm
/*
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* File : findbit.S
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* This file is part of RT-Thread RTOS
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* COPYRIGHT (C) 2006, RT-Thread Development Team
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Change Logs:
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* Date Author Notes
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* 2010-11-13 weety first version
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*/
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//#include <rtthread.h>
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//.text
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/*
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* Purpose : Find a 'zero' bit
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* Prototype: int find_first_zero_bit(void *addr, unsigned int maxbit);
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*/
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.globl _find_first_zero_bit_le
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_find_first_zero_bit_le:
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teq r1, #0
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beq 3f
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mov r2, #0
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1:
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ldrb r3, [r0, r2, lsr #3]
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lsr r3, r2, #3
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ldrb r3, [r0, r3]
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eors r3, r3, #0xff @ invert bits
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bne .L_found @ any now set - found zero bit
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add r2, r2, #8 @ next bit pointer
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2: cmp r2, r1 @ any more?
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blo 1b
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3: mov r0, r1 @ no free bits
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mov pc, lr
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//ENDPROC(_find_first_zero_bit_le)
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/*
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* Purpose : Find next 'zero' bit
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* Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int offset)
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*/
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.globl _find_next_zero_bit_le
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_find_next_zero_bit_le:
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teq r1, #0
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beq 3b
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ands ip, r2, #7
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beq 1b @ If new byte, goto old routine
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ldrb r3, [r0, r2, lsr #3]
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lsr r3, r2, #3
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ldrb r3, [r0, r3]
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eor r3, r3, #0xff @ now looking for a 1 bit
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movs r3, r3, lsr ip @ shift off unused bits
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bne .L_found
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orr r2, r2, #7 @ if zero, then no bits here
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add r2, r2, #1 @ align bit pointer
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b 2b @ loop for next bit
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//ENDPROC(_find_next_zero_bit_le)
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/*
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* Purpose : Find a 'one' bit
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* Prototype: int find_first_bit(const unsigned long *addr, unsigned int maxbit);
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*/
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.globl _find_first_bit_le
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_find_first_bit_le:
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teq r1, #0
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beq 3f
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mov r2, #0
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1:
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ldrb r3, [r0, r2, lsr #3]
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lsr r3, r2, #3
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ldrb r3, [r0, r3]
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movs r3, r3
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bne .L_found @ any now set - found zero bit
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add r2, r2, #8 @ next bit pointer
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2: cmp r2, r1 @ any more?
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blo 1b
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3: mov r0, r1 @ no free bits
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mov pc, lr
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//ENDPROC(_find_first_bit_le)
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/*
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* Purpose : Find next 'one' bit
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* Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int offset)
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*/
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.globl _find_next_bit_le
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_find_next_bit_le:
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teq r1, #0
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beq 3b
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ands ip, r2, #7
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beq 1b @ If new byte, goto old routine
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ldrb r3, [r0, r2, lsr #3]
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lsr r3, r2, #3
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ldrb r3, [r0, r3]
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movs r3, r3, lsr ip @ shift off unused bits
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bne .L_found
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orr r2, r2, #7 @ if zero, then no bits here
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add r2, r2, #1 @ align bit pointer
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b 2b @ loop for next bit
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//ENDPROC(_find_next_bit_le)
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#ifdef __ARMEB__
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ENTRY(_find_first_zero_bit_be)
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teq r1, #0
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beq 3f
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mov r2, #0
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1: eor r3, r2, #0x18 @ big endian byte ordering
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ARM( ldrb r3, [r0, r3, lsr #3] )
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THUMB( lsr r3, #3 )
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THUMB( ldrb r3, [r0, r3] )
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eors r3, r3, #0xff @ invert bits
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bne .L_found @ any now set - found zero bit
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add r2, r2, #8 @ next bit pointer
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2: cmp r2, r1 @ any more?
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blo 1b
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3: mov r0, r1 @ no free bits
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mov pc, lr
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ENDPROC(_find_first_zero_bit_be)
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ENTRY(_find_next_zero_bit_be)
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teq r1, #0
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beq 3b
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ands ip, r2, #7
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beq 1b @ If new byte, goto old routine
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eor r3, r2, #0x18 @ big endian byte ordering
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ARM( ldrb r3, [r0, r3, lsr #3] )
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THUMB( lsr r3, #3 )
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THUMB( ldrb r3, [r0, r3] )
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eor r3, r3, #0xff @ now looking for a 1 bit
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movs r3, r3, lsr ip @ shift off unused bits
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bne .L_found
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orr r2, r2, #7 @ if zero, then no bits here
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add r2, r2, #1 @ align bit pointer
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b 2b @ loop for next bit
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ENDPROC(_find_next_zero_bit_be)
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ENTRY(_find_first_bit_be)
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teq r1, #0
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beq 3f
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mov r2, #0
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1: eor r3, r2, #0x18 @ big endian byte ordering
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ARM( ldrb r3, [r0, r3, lsr #3] )
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THUMB( lsr r3, #3 )
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THUMB( ldrb r3, [r0, r3] )
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movs r3, r3
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bne .L_found @ any now set - found zero bit
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add r2, r2, #8 @ next bit pointer
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2: cmp r2, r1 @ any more?
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blo 1b
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3: mov r0, r1 @ no free bits
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mov pc, lr
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ENDPROC(_find_first_bit_be)
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ENTRY(_find_next_bit_be)
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teq r1, #0
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beq 3b
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ands ip, r2, #7
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beq 1b @ If new byte, goto old routine
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eor r3, r2, #0x18 @ big endian byte ordering
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ARM( ldrb r3, [r0, r3, lsr #3] )
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THUMB( lsr r3, #3 )
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THUMB( ldrb r3, [r0, r3] )
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movs r3, r3, lsr ip @ shift off unused bits
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bne .L_found
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orr r2, r2, #7 @ if zero, then no bits here
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add r2, r2, #1 @ align bit pointer
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b 2b @ loop for next bit
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ENDPROC(_find_next_bit_be)
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#endif
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/*
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* One or more bits in the LSB of r3 are assumed to be set.
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*/
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.L_found:
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#if 1 //__LINUX_ARM_ARCH__ >= 5
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rsb r0, r3, #0
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and r3, r3, r0
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clz r3, r3
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rsb r3, r3, #31
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add r0, r2, r3
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#else
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tst r3, #0x0f
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addeq r2, r2, #4
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movne r3, r3, lsl #4
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tst r3, #0x30
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addeq r2, r2, #2
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movne r3, r3, lsl #2
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tst r3, #0x40
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addeq r2, r2, #1
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mov r0, r2
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#endif
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cmp r1, r0 @ Clamp to maxbit
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movlo r0, r1
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mov pc, lr
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