1/*
2 * Copyright (c) 2003-2005 Apple Computer, Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28
29#include <sys/appleapiopts.h>
30#include <ppc/asm.h>					// EXT, LEXT
31#include <machine/cpu_capabilities.h>
32#include <machine/commpage.h>
33
34/* The red zone is used to move data between GPRs and FPRs: */
35
36#define	rzTicks			-8			// elapsed ticks since timestamp (double)
37#define	rzSeconds		-16			// seconds since timestamp (double)
38#define	rzUSeconds		-24			// useconds since timestamp (double)
39
40
41        .text
42        .align	2
43
44
45// *********************************
46// * G E T T I M E O F D A Y _ 3 2 *
47// *********************************
48//
49// This is a subroutine of gettimeofday.c that gets the seconds and microseconds
50// in user mode, usually without having to make a system call.  We do not deal with
51// the timezone.  The kernel maintains the following values in the comm page:
52//
53//	_COMM_PAGE_TIMESTAMP = 64 bit seconds timestamp
54//
55//	_COMM_PAGE_TIMEBASE = the timebase at which the timestamp was valid
56//
57//	_COMM_PAGE_SEC_PER_TICK = multiply timebase ticks by this to get seconds (double)
58//
59//	_COMM_PAGE_2_TO_52 = double precision constant 2**52
60//
61//	_COMM_PAGE_10_TO_6 = double precision constant 10**6
62//
63// We have to be careful to read these values atomically.  The kernel updates them
64// asynchronously to account for drift or time changes (eg, ntp.)  We adopt the
65// convention that (timebase==0) means the timestamp is invalid, in which case we
66// return a bad status so our caller can make the system call.
67//
68//		r3 = ptr to user's timeval structure (should not be null)
69
70gettimeofday_32:								// int gettimeofday(timeval *tp);
710:
72        lwz		r5,_COMM_PAGE_TIMEBASE+0(0)		// r5,r6 = TBR at timestamp
73        lwz		r6,_COMM_PAGE_TIMEBASE+4(0)
74        lwz		r8,_COMM_PAGE_TIMESTAMP+4(0)	// r8 = timestamp 32 bit seconds
75        lfd		f1,_COMM_PAGE_SEC_PER_TICK(0)
761:
77        mftbu	r10								// r10,r11 = current timebase
78        mftb	r11
79        mftbu	r12
80        cmplw	r10,r12
81        bne-	1b
82        or.		r0,r5,r6						// timebase 0? (ie, is timestamp invalid?)
83
84        sync									// create a barrier (patched to NOP if UP)
85
86        lwz		r0,_COMM_PAGE_TIMEBASE+0(0)		// then load data a 2nd time
87        lwz		r12,_COMM_PAGE_TIMEBASE+4(0)
88        lwz		r9,_COMM_PAGE_TIMESTAMP+4(0)
89        cmplw	cr6,r5,r0			// did we read a consistent set?
90        cmplw	cr7,r6,r12
91        beq-	3f					// timestamp is disabled so return bad status
92        cmplw	cr5,r9,r8
93        crand	cr0_eq,cr6_eq,cr7_eq
94        crand	cr0_eq,cr0_eq,cr5_eq
95        bne-	0b					// loop until we have a consistent set of data
96
97        subfc	r11,r6,r11			// compute ticks since timestamp
98        lwz		r9,_COMM_PAGE_2_TO_52(0)	// get exponent for (2**52)
99        subfe	r10,r5,r10			// complete 64-bit subtract
100        lfd		f2,_COMM_PAGE_2_TO_52(0)	// f2 <- (2**52)
101        srwi.	r0,r10,2			// if more than 2**34 ticks have elapsed...
102        stw		r11,rzTicks+4(r1)	// store elapsed ticks into red zone
103        or		r10,r10,r9			// convert long-long in (r10,r11) into double
104        bne-	3f					// ...call kernel to reprime timestamp
105
106        stw		r10,rzTicks(r1)		// complete double
107
108		mffs	f7
109		mtfsfi	7,1
110        lfd		f3,rzTicks(r1)		// get elapsed ticks since timestamp + 2**52
111        fsub	f4,f3,f2			// subtract 2**52 and normalize
112        fmul	f5,f4,f1			// f5 <- elapsed seconds since timestamp
113        lfd		f3,_COMM_PAGE_10_TO_6(0)	// get 10**6
114        fctiwz	f6,f5				// convert to integer
115        stfd	f6,rzSeconds(r1)	// store integer seconds into red zone
116        stw		r9,rzSeconds(r1)	// prepare to reload as floating pt
117        lfd		f6,rzSeconds(r1)	// get seconds + 2**52
118        fsub	f6,f6,f2			// f6 <- integral seconds
119        fsub	f6,f5,f6			// f6 <- fractional part of elapsed seconds
120        fmul	f6,f6,f3			// f6 <- fractional elapsed useconds
121        fctiwz	f6,f6				// convert useconds to integer
122        stfd	f6,rzUSeconds(r1)	// store useconds into red zone
123		mtfsf	0xff,f7
124
125        lwz		r5,rzSeconds+4(r1)	// r5 <- seconds since timestamp
126        lwz		r7,rzUSeconds+4(r1)	// r7 <- useconds since timestamp
127        add		r6,r8,r5			// add elapsed seconds to timestamp seconds
128
129        stw		r6,0(r3)			// store secs//usecs into user's timeval
130        stw		r7,4(r3)
131        li		r3,0				// return success
132        blr
1333:									// too long since last timestamp or this code is disabled
134        li		r3,1				// return bad status so our caller will make syscall
135        blr
136
137	COMMPAGE_DESCRIPTOR(gettimeofday_32,_COMM_PAGE_GETTIMEOFDAY,0,k64Bit,kCommPageSYNC+kCommPage32)
138
139
140// ***************************************
141// * G E T T I M E O F D A Y _ G 5 _ 3 2 *
142// ***************************************
143//
144// This routine is called in 32-bit mode on 64-bit processors.  A timeval is a struct of
145// a long seconds and int useconds, so its size depends on mode.
146
147gettimeofday_g5_32:							// int gettimeofday(timeval *tp);
1480:
149        ld		r6,_COMM_PAGE_TIMEBASE(0)	// r6 = TBR at timestamp
150        ld		r8,_COMM_PAGE_TIMESTAMP(0)	// r8 = timestamp (seconds)
151        lfd		f1,_COMM_PAGE_SEC_PER_TICK(0)
152        mftb	r10							// r10 = get current timebase
153        lwsync								// create a barrier if MP (patched to NOP if UP)
154        ld		r11,_COMM_PAGE_TIMEBASE(0)	// then get data a 2nd time
155        ld		r12,_COMM_PAGE_TIMESTAMP(0)
156        cmpdi	cr1,r6,0			// is the timestamp disabled?
157        cmpld	cr6,r6,r11			// did we read a consistent set?
158        cmpld	cr7,r8,r12
159        beq--	cr1,3f				// exit if timestamp disabled
160        crand	cr6_eq,cr7_eq,cr6_eq
161        sub		r11,r10,r6			// compute elapsed ticks from timestamp
162        bne--	cr6,0b				// loop until we have a consistent set of data
163
164        srdi.	r0,r11,35			// has it been more than 2**35 ticks since last timestamp?
165        std		r11,rzTicks(r1)		// put ticks in redzone where we can "lfd" it
166        bne--	3f					// timestamp too old, so reprime
167
168		mffs	f7
169		mtfsfi	7,1
170        lfd		f3,rzTicks(r1)		// get elapsed ticks since timestamp (fixed pt)
171        fcfid	f4,f3				// float the tick count
172        fmul	f5,f4,f1			// f5 <- elapsed seconds since timestamp
173        lfd		f3,_COMM_PAGE_10_TO_6(0)	// get 10**6
174        fctidz	f6,f5				// convert integer seconds to fixed pt
175        stfd	f6,rzSeconds(r1)	// save fixed pt integer seconds in red zone
176        fcfid	f6,f6				// float the integer seconds
177        fsub	f6,f5,f6			// f6 <- fractional part of elapsed seconds
178        fmul	f6,f6,f3			// f6 <- fractional elapsed useconds
179        fctidz	f6,f6				// convert useconds to fixed pt integer
180        stfd	f6,rzUSeconds(r1)	// store useconds into red zone
181		mtfsf	0xff,f7
182
183        lwz		r5,rzSeconds+4(r1)	// r5 <- seconds since timestamp
184        lwz		r7,rzUSeconds+4(r1)	// r7 <- useconds since timestamp
185        add		r6,r8,r5			// add elapsed seconds to timestamp seconds
186
187        stw		r6,0(r3)			// store secs//usecs into user's timeval
188        stw		r7,4(r3)
189        li		r3,0				// return success
190        blr
1913:									// too long since last timestamp or this code is disabled
192        li		r3,1				// return bad status so our caller will make syscall
193        blr
194
195	COMMPAGE_DESCRIPTOR(gettimeofday_g5_32,_COMM_PAGE_GETTIMEOFDAY,k64Bit,0,kCommPageSYNC+kCommPage32)
196
197
198// ***************************************
199// * G E T T I M E O F D A Y _ G 5 _ 6 4 *
200// ***************************************
201//
202// This routine is called in 64-bit mode on 64-bit processors.  A timeval is a struct of
203// a long seconds and int useconds, so its size depends on mode.
204
205gettimeofday_g5_64:							// int gettimeofday(timeval *tp);
2060:
207        ld		r6,_COMM_PAGE_TIMEBASE(0)	// r6 = TBR at timestamp
208        ld		r8,_COMM_PAGE_TIMESTAMP(0)	// r8 = timestamp (seconds)
209        lfd		f1,_COMM_PAGE_SEC_PER_TICK(0)
210        mftb	r10							// r10 = get current timebase
211        lwsync								// create a barrier if MP (patched to NOP if UP)
212        ld		r11,_COMM_PAGE_TIMEBASE(0)	// then get data a 2nd time
213        ld		r12,_COMM_PAGE_TIMESTAMP(0)
214        cmpdi	cr1,r6,0			// is the timestamp disabled?
215        cmpld	cr6,r6,r11			// did we read a consistent set?
216        cmpld	cr7,r8,r12
217        beq--	cr1,3f				// exit if timestamp disabled
218        crand	cr6_eq,cr7_eq,cr6_eq
219        sub		r11,r10,r6			// compute elapsed ticks from timestamp
220        bne--	cr6,0b				// loop until we have a consistent set of data
221
222        srdi.	r0,r11,35			// has it been more than 2**35 ticks since last timestamp?
223        std		r11,rzTicks(r1)		// put ticks in redzone where we can "lfd" it
224        bne--	3f					// timestamp too old, so reprime
225
226		mffs	f7
227		mtfsfi	7,1
228        lfd		f3,rzTicks(r1)		// get elapsed ticks since timestamp (fixed pt)
229        fcfid	f4,f3				// float the tick count
230        fmul	f5,f4,f1			// f5 <- elapsed seconds since timestamp
231        lfd		f3,_COMM_PAGE_10_TO_6(0)	// get 10**6
232        fctidz	f6,f5				// convert integer seconds to fixed pt
233        stfd	f6,rzSeconds(r1)	// save fixed pt integer seconds in red zone
234        fcfid	f6,f6				// float the integer seconds
235        fsub	f6,f5,f6			// f6 <- fractional part of elapsed seconds
236        fmul	f6,f6,f3			// f6 <- fractional elapsed useconds
237        fctidz	f6,f6				// convert useconds to fixed pt integer
238        stfd	f6,rzUSeconds(r1)	// store useconds into red zone
239		mtfsf	0xff,f7
240
241        lwz		r5,rzSeconds+4(r1)	// r5 <- seconds since timestamp
242        lwz		r7,rzUSeconds+4(r1)	// r7 <- useconds since timestamp
243        add		r6,r8,r5			// add elapsed seconds to timestamp seconds
244
245        std		r6,0(r3)			// store secs//usecs into user's timeval
246        stw		r7,8(r3)
247        li		r3,0				// return success
248        blr
2493:									// too long since last timestamp or this code is disabled
250        li		r3,1				// return bad status so our caller will make syscall
251        blr
252
253	COMMPAGE_DESCRIPTOR(gettimeofday_g5_64,_COMM_PAGE_GETTIMEOFDAY,k64Bit,0,kCommPageSYNC+kCommPage64)
254
255
256