/* * Copyright (c) 2006-2021, RT-Thread Development Team * * SPDX-License-Identifier: Apache-2.0 * * Change Logs: * Date Author Notes * 2010-11-13 weety first version */ //#include <rtthread.h> //.text /* * Purpose : Find a 'zero' bit * Prototype: int find_first_zero_bit(void *addr, unsigned int maxbit); */ .globl _find_first_zero_bit_le _find_first_zero_bit_le: teq r1, #0 beq 3f mov r2, #0 1: ldrb r3, [r0, r2, lsr #3] lsr r3, r2, #3 ldrb r3, [r0, r3] eors r3, r3, #0xff @ invert bits bne .L_found @ any now set - found zero bit add r2, r2, #8 @ next bit pointer 2: cmp r2, r1 @ any more? blo 1b 3: mov r0, r1 @ no free bits mov pc, lr //ENDPROC(_find_first_zero_bit_le) /* * Purpose : Find next 'zero' bit * Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int offset) */ .globl _find_next_zero_bit_le _find_next_zero_bit_le: teq r1, #0 beq 3b ands ip, r2, #7 beq 1b @ If new byte, goto old routine ldrb r3, [r0, r2, lsr #3] lsr r3, r2, #3 ldrb r3, [r0, r3] eor r3, r3, #0xff @ now looking for a 1 bit movs r3, r3, lsr ip @ shift off unused bits bne .L_found orr r2, r2, #7 @ if zero, then no bits here add r2, r2, #1 @ align bit pointer b 2b @ loop for next bit //ENDPROC(_find_next_zero_bit_le) /* * Purpose : Find a 'one' bit * Prototype: int find_first_bit(const unsigned long *addr, unsigned int maxbit); */ .globl _find_first_bit_le _find_first_bit_le: teq r1, #0 beq 3f mov r2, #0 1: ldrb r3, [r0, r2, lsr #3] lsr r3, r2, #3 ldrb r3, [r0, r3] movs r3, r3 bne .L_found @ any now set - found zero bit add r2, r2, #8 @ next bit pointer 2: cmp r2, r1 @ any more? blo 1b 3: mov r0, r1 @ no free bits mov pc, lr //ENDPROC(_find_first_bit_le) /* * Purpose : Find next 'one' bit * Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int offset) */ .globl _find_next_bit_le _find_next_bit_le: teq r1, #0 beq 3b ands ip, r2, #7 beq 1b @ If new byte, goto old routine ldrb r3, [r0, r2, lsr #3] lsr r3, r2, #3 ldrb r3, [r0, r3] movs r3, r3, lsr ip @ shift off unused bits bne .L_found orr r2, r2, #7 @ if zero, then no bits here add r2, r2, #1 @ align bit pointer b 2b @ loop for next bit //ENDPROC(_find_next_bit_le) #ifdef __ARMEB__ ENTRY(_find_first_zero_bit_be) teq r1, #0 beq 3f mov r2, #0 1: eor r3, r2, #0x18 @ big endian byte ordering ARM( ldrb r3, [r0, r3, lsr #3] ) THUMB( lsr r3, #3 ) THUMB( ldrb r3, [r0, r3] ) eors r3, r3, #0xff @ invert bits bne .L_found @ any now set - found zero bit add r2, r2, #8 @ next bit pointer 2: cmp r2, r1 @ any more? blo 1b 3: mov r0, r1 @ no free bits mov pc, lr ENDPROC(_find_first_zero_bit_be) ENTRY(_find_next_zero_bit_be) teq r1, #0 beq 3b ands ip, r2, #7 beq 1b @ If new byte, goto old routine eor r3, r2, #0x18 @ big endian byte ordering ARM( ldrb r3, [r0, r3, lsr #3] ) THUMB( lsr r3, #3 ) THUMB( ldrb r3, [r0, r3] ) eor r3, r3, #0xff @ now looking for a 1 bit movs r3, r3, lsr ip @ shift off unused bits bne .L_found orr r2, r2, #7 @ if zero, then no bits here add r2, r2, #1 @ align bit pointer b 2b @ loop for next bit ENDPROC(_find_next_zero_bit_be) ENTRY(_find_first_bit_be) teq r1, #0 beq 3f mov r2, #0 1: eor r3, r2, #0x18 @ big endian byte ordering ARM( ldrb r3, [r0, r3, lsr #3] ) THUMB( lsr r3, #3 ) THUMB( ldrb r3, [r0, r3] ) movs r3, r3 bne .L_found @ any now set - found zero bit add r2, r2, #8 @ next bit pointer 2: cmp r2, r1 @ any more? blo 1b 3: mov r0, r1 @ no free bits mov pc, lr ENDPROC(_find_first_bit_be) ENTRY(_find_next_bit_be) teq r1, #0 beq 3b ands ip, r2, #7 beq 1b @ If new byte, goto old routine eor r3, r2, #0x18 @ big endian byte ordering ARM( ldrb r3, [r0, r3, lsr #3] ) THUMB( lsr r3, #3 ) THUMB( ldrb r3, [r0, r3] ) movs r3, r3, lsr ip @ shift off unused bits bne .L_found orr r2, r2, #7 @ if zero, then no bits here add r2, r2, #1 @ align bit pointer b 2b @ loop for next bit ENDPROC(_find_next_bit_be) #endif /* * One or more bits in the LSB of r3 are assumed to be set. */ .L_found: #if 1 //__LINUX_ARM_ARCH__ >= 5 rsb r0, r3, #0 and r3, r3, r0 clz r3, r3 rsb r3, r3, #31 add r0, r2, r3 #else tst r3, #0x0f addeq r2, r2, #4 movne r3, r3, lsl #4 tst r3, #0x30 addeq r2, r2, #2 movne r3, r3, lsl #2 tst r3, #0x40 addeq r2, r2, #1 mov r0, r2 #endif cmp r1, r0 @ Clamp to maxbit movlo r0, r1 mov pc, lr