/* * linux/arch/unicore32/lib/findbit.S * * Code specific to PKUnity SoC and UniCore ISA * * Copyright (C) 2001-2010 GUAN Xue-tao * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include <linux/linkage.h> #include <asm/assembler.h> .text /* * Purpose : Find a 'zero' bit * Prototype: int find_first_zero_bit(void *addr, unsigned int maxbit); */ ENTRY(find_first_zero_bit) cxor.a r1, #0 beq 3f mov r2, #0 1: ldb r3, [r0+], r2 >> #3 xor.a r3, r3, #0xff @ invert bits bne .L_found @ any now set - found zero bit add r2, r2, #8 @ next bit pointer 2: csub.a r2, r1 @ any more? bub 1b 3: mov r0, r1 @ no free bits mov pc, lr ENDPROC(find_first_zero_bit) /* * Purpose : Find next 'zero' bit * Prototype: int find_next_zero_bit * (void *addr, unsigned int maxbit, int offset) */ ENTRY(find_next_zero_bit) cxor.a r1, #0 beq 3b and.a ip, r2, #7 beq 1b @ If new byte, goto old routine ldb r3, [r0+], r2 >> #3 xor r3, r3, #0xff @ now looking for a 1 bit mov.a r3, r3 >> ip @ shift off unused bits bne .L_found or 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) /* * Purpose : Find a 'one' bit * Prototype: int find_first_bit * (const unsigned long *addr, unsigned int maxbit); */ ENTRY(find_first_bit) cxor.a r1, #0 beq 3f mov r2, #0 1: ldb r3, [r0+], r2 >> #3 mov.a r3, r3 bne .L_found @ any now set - found zero bit add r2, r2, #8 @ next bit pointer 2: csub.a r2, r1 @ any more? bub 1b 3: mov r0, r1 @ no free bits mov pc, lr ENDPROC(find_first_bit) /* * Purpose : Find next 'one' bit * Prototype: int find_next_zero_bit * (void *addr, unsigned int maxbit, int offset) */ ENTRY(find_next_bit) cxor.a r1, #0 beq 3b and.a ip, r2, #7 beq 1b @ If new byte, goto old routine ldb r3, [r0+], r2 >> #3 mov.a r3, r3 >> ip @ shift off unused bits bne .L_found or 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) /* * One or more bits in the LSB of r3 are assumed to be set. */ .L_found: rsub r1, r3, #0 and r3, r3, r1 cntlz r3, r3 rsub r3, r3, #31 add r0, r2, r3 mov pc, lr