diff options
Diffstat (limited to 'arch/arm/lib/findbit.S')
| -rw-r--r-- | arch/arm/lib/findbit.S | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/arch/arm/lib/findbit.S b/arch/arm/lib/findbit.S new file mode 100644 index 00000000..64f6bc1a --- /dev/null +++ b/arch/arm/lib/findbit.S @@ -0,0 +1,196 @@ +/* + * linux/arch/arm/lib/findbit.S + * + * Copyright (C) 1995-2000 Russell King + * + * 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. + * + * 16th March 2001 - John Ripley <jripley@sonicblue.com> + * Fixed so that "size" is an exclusive not an inclusive quantity. + * All users of these functions expect exclusive sizes, and may + * also call with zero size. + * Reworked by rmk. + */ +#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_le) + teq r1, #0 + beq 3f + mov r2, #0 +1: + ARM( ldrb r3, [r0, r2, lsr #3] ) + THUMB( lsr r3, r2, #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_le) + +/* + * Purpose : Find next 'zero' bit + * Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int offset) + */ +ENTRY(_find_next_zero_bit_le) + teq r1, #0 + beq 3b + ands ip, r2, #7 + beq 1b @ If new byte, goto old routine + ARM( ldrb r3, [r0, r2, lsr #3] ) + THUMB( lsr r3, r2, #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_le) + +/* + * Purpose : Find a 'one' bit + * Prototype: int find_first_bit(const unsigned long *addr, unsigned int maxbit); + */ +ENTRY(_find_first_bit_le) + teq r1, #0 + beq 3f + mov r2, #0 +1: + ARM( ldrb r3, [r0, r2, lsr #3] ) + THUMB( lsr r3, r2, #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_le) + +/* + * Purpose : Find next 'one' bit + * Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int offset) + */ +ENTRY(_find_next_bit_le) + teq r1, #0 + beq 3b + ands ip, r2, #7 + beq 1b @ If new byte, goto old routine + ARM( ldrb r3, [r0, r2, lsr #3] ) + THUMB( lsr r3, r2, #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_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 __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 + |