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59 lines
1.2 KiB
59 lines
1.2 KiB
20 years ago
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/*
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* linux/arch/arm/lib/delay.S
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*
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* Copyright (C) 1995, 1996 Russell King
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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.text
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LC0: .word loops_per_jiffy
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/*
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* 0 <= r0 <= 2000
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*/
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ENTRY(__udelay)
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mov r2, #0x6800
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orr r2, r2, #0x00db
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mul r0, r2, r0
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ENTRY(__const_udelay) @ 0 <= r0 <= 0x01ffffff
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ldr r2, LC0
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ldr r2, [r2] @ max = 0x0fffffff
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mov r0, r0, lsr #11 @ max = 0x00003fff
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mov r2, r2, lsr #11 @ max = 0x0003ffff
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mul r0, r2, r0 @ max = 2^32-1
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movs r0, r0, lsr #6
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RETINSTR(moveq,pc,lr)
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/*
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* loops = (r0 * 0x10c6 * 100 * loops_per_jiffy) / 2^32
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*
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* Oh, if only we had a cycle counter...
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*/
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@ Delay routine
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ENTRY(__delay)
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subs r0, r0, #1
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#if 0
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RETINSTR(movls,pc,lr)
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subs r0, r0, #1
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RETINSTR(movls,pc,lr)
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subs r0, r0, #1
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RETINSTR(movls,pc,lr)
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subs r0, r0, #1
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RETINSTR(movls,pc,lr)
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subs r0, r0, #1
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RETINSTR(movls,pc,lr)
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subs r0, r0, #1
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RETINSTR(movls,pc,lr)
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subs r0, r0, #1
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RETINSTR(movls,pc,lr)
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subs r0, r0, #1
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#endif
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bhi __delay
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RETINSTR(mov,pc,lr)
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