patch-2.4.0-test2 linux/arch/arm/lib/findbit.S

• Lines: 105
• Date: Mon Jun 19 17:59:34 2000
• Orig file: v2.4.0-test1/linux/arch/arm/lib/findbit.S
• Orig date: Thu Mar 2 14:36:22 2000

diff -u --recursive --new-file v2.4.0-test1/linux/arch/arm/lib/findbit.S linux/arch/arm/lib/findbit.S
@@ -1,65 +1,53 @@
 /*
- * linux/arch/arm/lib/bitops.S
+ * linux/arch/arm/lib/findbit.S
  *
- * Copyright (C) 1995-1996 Russell King
+ * Copyright (C) 1995-2000 Russell King
  */
 
 #include <linux/linkage.h>
 #include <asm/assembler.h>
                 .text
 
-@ Purpose  : Find a 'zero' bit
-@ Prototype: int find_first_zero_bit(char *addr,int maxbit);
-
+/*
+ * Purpose  : Find a 'zero' bit
+ * Prototype: int find_first_zero_bit(void *addr, int maxbit);
+ */
 ENTRY(find_first_zero_bit)
-		mov	r2, #0			@ Initialise bit position
-Lfindzbit1lp:	ldrb	r3, [r0, r2, lsr #3]	@ Check byte, if 0xFF, then all bits set
-		teq	r3, #0xFF
-		bne	Lfoundzbit
-		add	r2, r2, #8
-		cmp	r2, r1			@ Check to see if we have come to the end
-		bcc	Lfindzbit1lp
-		add	r0, r1, #1		@ Make sure that we flag an error
-		RETINSTR(mov,pc,lr)
-Lfoundzbit:	tst	r3, #1			@ Check individual bits
-		moveq	r0, r2
-		RETINSTR(moveq,pc,lr)
-		tst	r3, #2
-		addeq	r0, r2, #1
-		RETINSTR(moveq,pc,lr)
-		tst	r3, #4
-		addeq	r0, r2, #2
-		RETINSTR(moveq,pc,lr)
-		tst	r3, #8
-		addeq	r0, r2, #3
-		RETINSTR(moveq,pc,lr)
-		tst	r3, #16
-		addeq	r0, r2, #4
-		RETINSTR(moveq,pc,lr)
-		tst	r3, #32
-		addeq	r0, r2, #5
-		RETINSTR(moveq,pc,lr)
-		tst	r3, #64
-		addeq	r0, r2, #6
-		RETINSTR(moveq,pc,lr)
-		add	r0, r2, #7
+		mov	r2, #0
+.bytelp:	ldrb	r3, [r0, r2, lsr #3]
+		eors	r3, r3, #0xff		@ invert bits
+		bne	.found			@ any now set - found zero bit
+		add	r2, r2, #8		@ next bit pointer
+		cmp	r2, r1			@ any more?
+		bcc	.bytelp
+		add	r0, r1, #1		@ no free bits
 		RETINSTR(mov,pc,lr)
 
-@ Purpose  : Find next 'zero' bit
-@ Prototype: int find_next_zero_bit(char *addr,int maxbit,int offset)
-
+/*
+ * Purpose  : Find next 'zero' bit
+ * Prototype: int find_next_zero_bit(void *addr, int maxbit, int offset)
+ */
 ENTRY(find_next_zero_bit)
-		tst	r2, #7
-		beq	Lfindzbit1lp		@ If new byte, goto old routine
+		ands	ip, r2, #7
+		beq	.bytelp			@ If new byte, goto old routine
 		ldrb	r3, [r0, r2, lsr#3]
-		orr	r3, r3, #0xFF00		@ Set top bits so we wont get confused
-		str	r4, [sp, #-4]!
-		and	r4, r2, #7
-		mov	r3, r3, lsr r4		@ Shift right by no. of bits
-		ldr	r4, [sp], #4
-		and	r3, r3, #0xFF
-		teq	r3, #0xFF
-		orreq	r2, r2, #7
+		eor	r3, r3, #0xff		@ now looking for a 1 bit
+		movs	r3, r3, lsr ip		@ shift off unused bits
+		orreq	r2, r2, #7		@ if zero, then no bits here
+		addeq	r2, r2, #1		@ align bit pointer
+		beq	.bytelp			@ loop for next bit
+
+/*
+ * One or more bits in the LSB of r3 are assumed to be set.
+ */
+.found:		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
-		beq	Lfindzbit1lp		@ If all bits are set, goto old routine
-		b	Lfoundzbit
+		mov	r0, r2
+		RETINSTR(mov,pc,lr)
+