1/* 2 * linux/arch/unicore32/lib/findbit.S 3 * 4 * Code specific to PKUnity SoC and UniCore ISA 5 * 6 * Copyright (C) 2001-2010 GUAN Xue-tao 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License version 2 as 10 * published by the Free Software Foundation. 11 */ 12#include <linux/linkage.h> 13#include <asm/assembler.h> 14 .text 15 16/* 17 * Purpose : Find a 'zero' bit 18 * Prototype: int find_first_zero_bit(void *addr, unsigned int maxbit); 19 */ 20ENTRY(find_first_zero_bit) 21 cxor.a r1, #0 22 beq 3f 23 mov r2, #0 241: ldb r3, [r0+], r2 >> #3 25 xor.a r3, r3, #0xff @ invert bits 26 bne .L_found @ any now set - found zero bit 27 add r2, r2, #8 @ next bit pointer 282: csub.a r2, r1 @ any more? 29 bub 1b 303: mov r0, r1 @ no free bits 31 mov pc, lr 32ENDPROC(find_first_zero_bit) 33 34/* 35 * Purpose : Find next 'zero' bit 36 * Prototype: int find_next_zero_bit 37 * (void *addr, unsigned int maxbit, int offset) 38 */ 39ENTRY(find_next_zero_bit) 40 cxor.a r1, #0 41 beq 3b 42 and.a ip, r2, #7 43 beq 1b @ If new byte, goto old routine 44 ldb r3, [r0+], r2 >> #3 45 xor r3, r3, #0xff @ now looking for a 1 bit 46 mov.a r3, r3 >> ip @ shift off unused bits 47 bne .L_found 48 or r2, r2, #7 @ if zero, then no bits here 49 add r2, r2, #1 @ align bit pointer 50 b 2b @ loop for next bit 51ENDPROC(find_next_zero_bit) 52 53/* 54 * Purpose : Find a 'one' bit 55 * Prototype: int find_first_bit 56 * (const unsigned long *addr, unsigned int maxbit); 57 */ 58ENTRY(find_first_bit) 59 cxor.a r1, #0 60 beq 3f 61 mov r2, #0 621: ldb r3, [r0+], r2 >> #3 63 mov.a r3, r3 64 bne .L_found @ any now set - found zero bit 65 add r2, r2, #8 @ next bit pointer 662: csub.a r2, r1 @ any more? 67 bub 1b 683: mov r0, r1 @ no free bits 69 mov pc, lr 70ENDPROC(find_first_bit) 71 72/* 73 * Purpose : Find next 'one' bit 74 * Prototype: int find_next_zero_bit 75 * (void *addr, unsigned int maxbit, int offset) 76 */ 77ENTRY(find_next_bit) 78 cxor.a r1, #0 79 beq 3b 80 and.a ip, r2, #7 81 beq 1b @ If new byte, goto old routine 82 ldb r3, [r0+], r2 >> #3 83 mov.a r3, r3 >> ip @ shift off unused bits 84 bne .L_found 85 or r2, r2, #7 @ if zero, then no bits here 86 add r2, r2, #1 @ align bit pointer 87 b 2b @ loop for next bit 88ENDPROC(find_next_bit) 89 90/* 91 * One or more bits in the LSB of r3 are assumed to be set. 92 */ 93.L_found: 94 rsub r1, r3, #0 95 and r3, r3, r1 96 cntlz r3, r3 97 rsub r3, r3, #31 98 add r0, r2, r3 99 mov pc, lr 100 101