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/*
 *  window.s
 *
 *  This file contains the register window management routines for the
 *  SPARC architecture.  Trap handlers for the following capabilities
 *  are included in this file:
 *
 *    + Window Overflow
 *    + Window Underflow
 *    + Flushing All Windows
 *
 *  COPYRIGHT:
 *
 *  This file includes the window overflow and underflow handlers from
 *  the file srt0.s provided with the binary distribution of the SPARC
 *  Instruction Simulator (SIS) found at
 *  ftp://ftp.estec.esa.nl/pub/ws/wsd/erc32.
 *
 *  COPYRIGHT (c) 1995. European Space Agency.
 *
 *  This terms of the RTEMS license apply to this file.
 *
 *  $Id: window.S,v 1.2 2001-09-27 12:01:39 chris Exp $
 */
 
#include 
 
        .seg    "text"
        /*
         *  Window overflow trap handler.
         *
         *  On entry:
         *
         *    l0 = psr (from trap table)
         *    l1 = pc
         *    l2 = npc
         */
 
        PUBLIC(window_overflow_trap_handler)
 
SYM(window_overflow_trap_handler):
 
        /*
         *  Calculate new WIM by "rotating" the valid bits in the WIM right
         *  by one position.  The following shows how the bits move for a SPARC
         *  cpu implementation where SPARC_NUMBER_OF_REGISTER_WINDOWS is 8.
         *
         *    OLD WIM = 76543210
         *    NEW WIM = 07654321
         *
         *  NOTE: New WIM must be stored in a global register since the
         *        "save" instruction just prior to the load of the wim
         *        register will result in the local register set changing.
         */
 
        mov  %wim, %l3                   ! l3 = WIM
        mov  %g1, %l7                    ! save g1
        srl  %l3, 1, %g1                 ! g1 = WIM >> 1
        sll  %l3, SPARC_NUMBER_OF_REGISTER_WINDOWS-1 , %l4
                                         ! l4 = WIM << (Number Windows - 1)
        or   %l4, %g1, %g1               ! g1 = (WIM >> 1) |
                                         !      (WIM << (Number Windows - 1))
 
        save                             ! Get into window to be saved.
        mov  %g1, %wim                   ! load new WIM
        nop; nop; nop                    ! 3 slot delay
        std  %l0, [%sp + 0x00]           ! save local register set
        std  %l2, [%sp + 0x08]
        std  %l4, [%sp + 0x10]
        std  %l6, [%sp + 0x18]
        std  %i0, [%sp + 0x20]           ! save input register set
        std  %i2, [%sp + 0x28]
        std  %i4, [%sp + 0x30]
        std  %i6, [%sp + 0x38]
        restore                          ! Go back to trap window.
        mov  %l7, %g1                    ! restore g1
        jmp  %l1                         ! Re-execute save.
        rett %l2
 
        /*
         *  Window underflow trap handler.
         *
         *  On entry:
         *
         *    l0 = psr (from trap table)
         *    l1 = pc
         *    l2 = npc
         */
 
        PUBLIC(window_underflow_trap_handler)
 
SYM(window_underflow_trap_handler):
 
        /*
         *  Calculate new WIM by "rotating" the valid bits in the WIM left
         *  by one position.  The following shows how the bits move for a SPARC
         *  cpu implementation where SPARC_NUMBER_OF_REGISTER_WINDOWS is 8.
         *
         *    OLD WIM = 76543210
         *    NEW WIM = 07654321
         *
         *  NOTE: New WIM must be stored in a global register since the
         *        "save" instruction just prior to the load of the wim
         *        register will result in the local register set changing.
         */
 
        mov  %wim, %l3                  ! Calculate new WIM
        sll  %l3, 1, %l4                ! l4 = WIM << 1
        srl  %l3, SPARC_NUMBER_OF_REGISTER_WINDOWS-1, %l5
                                        ! l5 = WIM >> (Number Windows-1)
        or   %l5, %l4, %l5              ! l5 = (WIM << 1) |
                                        !      (WIM >> (Number Windows-1))
        mov  %l5, %wim                  ! load the new WIM
        nop; nop; nop
        restore                         ! Two restores to get into the
        restore                         ! window to restore
        ldd  [%sp + 0x00], %l0          ! First the local register set
        ldd  [%sp + 0x08], %l2
        ldd  [%sp + 0x10], %l4
        ldd  [%sp + 0x18], %l6
        ldd  [%sp + 0x20], %i0          ! Then the input registers
        ldd  [%sp + 0x28], %i2
        ldd  [%sp + 0x30], %i4
        ldd  [%sp + 0x38], %i6
        save                            ! Get back to the trap window.
        save
        jmp  %l1                        ! Re-execute restore.
        rett  %l2
 
        /*
         *  Flush All Windows trap handler.
         *
         *  Flush all windows with valid contents except the current one
         *  and the one we will be returning to.
         *
         *  In examining the set register windows, one may logically divide
         *  the windows into sets (some of which may be empty) based on their
         *  current status:
         *
         *    + current (i.e. in use),
         *    + used (i.e. a restore would not trap)
         *    + invalid (i.e. 1 in corresponding bit in WIM)
         *    + unused
         *
         *  Either the used or unused set of windows may be empty.
         *
         *  NOTE: We assume only one bit is set in the WIM at a time.
         *
         *  Given a CWP of 5 and a WIM of 0x1, the registers are divided
         *  into sets as follows:
         *
         *    + 0   - invalid
         *    + 1-4 - unused
         *    + 5   - current
         *    + 6-7 - used
         *
         *  In this case, we only would save the used windows which we
         *  will not be returning to -- 6.
         *
         *    Register Usage while saving the windows:
         *      g1 = current PSR
         *      g2 = current wim
         *      g3 = CWP
         *      g4 = wim scratch
         *      g5 = scratch
         *
         *  On entry:
         *
         *    l0 = psr (from trap table)
         *    l1 = pc
         *    l2 = npc
         */
 
        PUBLIC(window_flush_trap_handler)
 
SYM(window_flush_trap_handler):
        /*
         *  Save the global registers we will be using
         */
 
        mov     %g1, %l3
        mov     %g2, %l4
        mov     %g3, %l5
        mov     %g4, %l6
        mov     %g5, %l7
 
        mov     %l0, %g1                      ! g1 = psr
        mov     %wim, %g2                     ! g2 = wim
        and     %l0, SPARC_PSR_CWP_MASK, %g3  ! g3 = CWP
 
        add     %g3, 1, %g5                   ! g5 = CWP + 1
        and     %g5, SPARC_NUMBER_OF_REGISTER_WINDOWS - 1, %g5
 
        mov     1, %g4
        sll     %g4, %g5, %g4                 ! g4 = WIM mask for CWP+1 invalid
 
        restore                               ! go back one register window
 
save_frame_loop:
        sll     %g4, 1, %g5                   ! rotate the "wim" left 1
        srl     %g4, SPARC_NUMBER_OF_REGISTER_WINDOWS - 1, %g4
        or      %g4, %g5, %g4                 ! g4 = wim if we do one restore
 
        /*
         *  If a restore would not underflow, then continue.
         */
 
        andcc   %g4, %g2, %g0                 ! Any windows to flush?
        bnz     done_flushing                 ! No, then continue
        nop
 
        restore                               ! back one window
 
        /*
         *  Now save the window just as if we overflowed to it.
         */
 
        std     %l0, [%sp + CPU_STACK_FRAME_L0_OFFSET]
        std     %l2, [%sp + CPU_STACK_FRAME_L2_OFFSET]
        std     %l4, [%sp + CPU_STACK_FRAME_L4_OFFSET]
        std     %l6, [%sp + CPU_STACK_FRAME_L6_OFFSET]
 
        std     %i0, [%sp + CPU_STACK_FRAME_I0_OFFSET]
        std     %i2, [%sp + CPU_STACK_FRAME_I2_OFFSET]
        std     %i4, [%sp + CPU_STACK_FRAME_I4_OFFSET]
        std     %i6, [%sp + CPU_STACK_FRAME_I6_FP_OFFSET]
 
        ba      save_frame_loop
        nop
 
done_flushing:
 
        add     %g3, 2, %g3                   ! calculate desired WIM
        and     %g3, SPARC_NUMBER_OF_REGISTER_WINDOWS - 1, %g3
        mov     1, %g4
        sll     %g4, %g3, %g4                 ! g4 = new WIM
        mov     %g4, %wim
 
        mov     %g1, %psr                     ! restore PSR
        nop
        nop
        nop
 
        /*
         *  Restore the global registers we used
         */
 
        mov     %l3, %g1
        mov     %l4, %g2
        mov     %l5, %g3
        mov     %l6, %g4
        mov     %l7, %g5
 
        jmpl    %l2, %g0
        rett    %l2 + 4
 
/* end of file */

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[/] [openrisc/] [trunk/] [rtos/] [rtems/] [c/] [src/] [lib/] [libcpu/] [sparc/] [reg_win/] [window.S] - Blame information for rev 307

Line No.	Rev	Author	Line
1	30	unneback	`/*`
2			`* window.s`
3			`*`
4			`* This file contains the register window management routines for the`
5			`* SPARC architecture. Trap handlers for the following capabilities`
6			`* are included in this file:`
7			`*`
8			`* + Window Overflow`
9			`* + Window Underflow`
10			`* + Flushing All Windows`
11			`*`
12			`* COPYRIGHT:`
13			`*`
14			`* This file includes the window overflow and underflow handlers from`
15			`* the file srt0.s provided with the binary distribution of the SPARC`
16			`* Instruction Simulator (SIS) found at`
17			`* ftp://ftp.estec.esa.nl/pub/ws/wsd/erc32.`
18			`*`
19			`* COPYRIGHT (c) 1995. European Space Agency.`
20			`*`
21			`* This terms of the RTEMS license apply to this file.`
22			`*`
23			`* $Id: window.S,v 1.2 2001-09-27 12:01:39 chris Exp $`
24			`*/`
25
26			`#include`
27
28			`.seg "text"`
29			`/*`
30			`* Window overflow trap handler.`
31			`*`
32			`* On entry:`
33			`*`
34			`* l0 = psr (from trap table)`
35			`* l1 = pc`
36			`* l2 = npc`
37			`*/`
38
39			`PUBLIC(window_overflow_trap_handler)`
40
41			`SYM(window_overflow_trap_handler):`
42
43			`/*`
44			`* Calculate new WIM by "rotating" the valid bits in the WIM right`
45			`* by one position. The following shows how the bits move for a SPARC`
46			`* cpu implementation where SPARC_NUMBER_OF_REGISTER_WINDOWS is 8.`
47			`*`
48			`* OLD WIM = 76543210`
49			`* NEW WIM = 07654321`
50			`*`
51			`* NOTE: New WIM must be stored in a global register since the`
52			`* "save" instruction just prior to the load of the wim`
53			`* register will result in the local register set changing.`
54			`*/`
55
56			`mov %wim, %l3 ! l3 = WIM`
57			`mov %g1, %l7 ! save g1`
58			`srl %l3, 1, %g1 ! g1 = WIM >> 1`
59			`sll %l3, SPARC_NUMBER_OF_REGISTER_WINDOWS-1 , %l4`
60			`! l4 = WIM << (Number Windows - 1)`
61			`or %l4, %g1, %g1 ! g1 = (WIM >> 1) \|`
62			`! (WIM << (Number Windows - 1))`
63
64			`save ! Get into window to be saved.`
65			`mov %g1, %wim ! load new WIM`
66			`nop; nop; nop ! 3 slot delay`
67			`std %l0, [%sp + 0x00] ! save local register set`
68			`std %l2, [%sp + 0x08]`
69			`std %l4, [%sp + 0x10]`
70			`std %l6, [%sp + 0x18]`
71			`std %i0, [%sp + 0x20] ! save input register set`
72			`std %i2, [%sp + 0x28]`
73			`std %i4, [%sp + 0x30]`
74			`std %i6, [%sp + 0x38]`
75			`restore ! Go back to trap window.`
76			`mov %l7, %g1 ! restore g1`
77			`jmp %l1 ! Re-execute save.`
78			`rett %l2`
79
80			`/*`
81			`* Window underflow trap handler.`
82			`*`
83			`* On entry:`
84			`*`
85			`* l0 = psr (from trap table)`
86			`* l1 = pc`
87			`* l2 = npc`
88			`*/`
89
90			`PUBLIC(window_underflow_trap_handler)`
91
92			`SYM(window_underflow_trap_handler):`
93
94			`/*`
95			`* Calculate new WIM by "rotating" the valid bits in the WIM left`
96			`* by one position. The following shows how the bits move for a SPARC`
97			`* cpu implementation where SPARC_NUMBER_OF_REGISTER_WINDOWS is 8.`
98			`*`
99			`* OLD WIM = 76543210`
100			`* NEW WIM = 07654321`
101			`*`
102			`* NOTE: New WIM must be stored in a global register since the`
103			`* "save" instruction just prior to the load of the wim`
104			`* register will result in the local register set changing.`
105			`*/`
106
107			`mov %wim, %l3 ! Calculate new WIM`
108			`sll %l3, 1, %l4 ! l4 = WIM << 1`
109			`srl %l3, SPARC_NUMBER_OF_REGISTER_WINDOWS-1, %l5`
110			`! l5 = WIM >> (Number Windows-1)`
111			`or %l5, %l4, %l5 ! l5 = (WIM << 1) \|`
112			`! (WIM >> (Number Windows-1))`
113			`mov %l5, %wim ! load the new WIM`
114			`nop; nop; nop`
115			`restore ! Two restores to get into the`
116			`restore ! window to restore`
117			`ldd [%sp + 0x00], %l0 ! First the local register set`
118			`ldd [%sp + 0x08], %l2`
119			`ldd [%sp + 0x10], %l4`
120			`ldd [%sp + 0x18], %l6`
121			`ldd [%sp + 0x20], %i0 ! Then the input registers`
122			`ldd [%sp + 0x28], %i2`
123			`ldd [%sp + 0x30], %i4`
124			`ldd [%sp + 0x38], %i6`
125			`save ! Get back to the trap window.`
126			`save`
127			`jmp %l1 ! Re-execute restore.`
128			`rett %l2`
129
130			`/*`
131			`* Flush All Windows trap handler.`
132			`*`
133			`* Flush all windows with valid contents except the current one`
134			`* and the one we will be returning to.`
135			`*`
136			`* In examining the set register windows, one may logically divide`
137			`* the windows into sets (some of which may be empty) based on their`
138			`* current status:`
139			`*`
140			`* + current (i.e. in use),`
141			`* + used (i.e. a restore would not trap)`
142			`* + invalid (i.e. 1 in corresponding bit in WIM)`
143			`* + unused`
144			`*`
145			`* Either the used or unused set of windows may be empty.`
146			`*`
147			`* NOTE: We assume only one bit is set in the WIM at a time.`
148			`*`
149			`* Given a CWP of 5 and a WIM of 0x1, the registers are divided`
150			`* into sets as follows:`
151			`*`
152			`* + 0 - invalid`
153			`* + 1-4 - unused`
154			`* + 5 - current`
155			`* + 6-7 - used`
156			`*`
157			`* In this case, we only would save the used windows which we`
158			`* will not be returning to -- 6.`
159			`*`
160			`* Register Usage while saving the windows:`
161			`* g1 = current PSR`
162			`* g2 = current wim`
163			`* g3 = CWP`
164			`* g4 = wim scratch`
165			`* g5 = scratch`
166			`*`
167			`* On entry:`
168			`*`
169			`* l0 = psr (from trap table)`
170			`* l1 = pc`
171			`* l2 = npc`
172			`*/`
173
174			`PUBLIC(window_flush_trap_handler)`
175
176			`SYM(window_flush_trap_handler):`
177			`/*`
178			`* Save the global registers we will be using`
179			`*/`
180
181			`mov %g1, %l3`
182			`mov %g2, %l4`
183			`mov %g3, %l5`
184			`mov %g4, %l6`
185			`mov %g5, %l7`
186
187			`mov %l0, %g1 ! g1 = psr`
188			`mov %wim, %g2 ! g2 = wim`
189			`and %l0, SPARC_PSR_CWP_MASK, %g3 ! g3 = CWP`
190
191			`add %g3, 1, %g5 ! g5 = CWP + 1`
192			`and %g5, SPARC_NUMBER_OF_REGISTER_WINDOWS - 1, %g5`
193
194			`mov 1, %g4`
195			`sll %g4, %g5, %g4 ! g4 = WIM mask for CWP+1 invalid`
196
197			`restore ! go back one register window`
198
199			`save_frame_loop:`
200			`sll %g4, 1, %g5 ! rotate the "wim" left 1`
201			`srl %g4, SPARC_NUMBER_OF_REGISTER_WINDOWS - 1, %g4`
202			`or %g4, %g5, %g4 ! g4 = wim if we do one restore`
203
204			`/*`
205			`* If a restore would not underflow, then continue.`
206			`*/`
207
208			`andcc %g4, %g2, %g0 ! Any windows to flush?`
209			`bnz done_flushing ! No, then continue`
210			`nop`
211
212			`restore ! back one window`
213
214			`/*`
215			`* Now save the window just as if we overflowed to it.`
216			`*/`
217
218			`std %l0, [%sp + CPU_STACK_FRAME_L0_OFFSET]`
219			`std %l2, [%sp + CPU_STACK_FRAME_L2_OFFSET]`
220			`std %l4, [%sp + CPU_STACK_FRAME_L4_OFFSET]`
221			`std %l6, [%sp + CPU_STACK_FRAME_L6_OFFSET]`
222
223			`std %i0, [%sp + CPU_STACK_FRAME_I0_OFFSET]`
224			`std %i2, [%sp + CPU_STACK_FRAME_I2_OFFSET]`
225			`std %i4, [%sp + CPU_STACK_FRAME_I4_OFFSET]`
226			`std %i6, [%sp + CPU_STACK_FRAME_I6_FP_OFFSET]`
227
228			`ba save_frame_loop`
229			`nop`
230
231			`done_flushing:`
232
233			`add %g3, 2, %g3 ! calculate desired WIM`
234			`and %g3, SPARC_NUMBER_OF_REGISTER_WINDOWS - 1, %g3`
235			`mov 1, %g4`
236			`sll %g4, %g3, %g4 ! g4 = new WIM`
237			`mov %g4, %wim`
238
239			`mov %g1, %psr ! restore PSR`
240			`nop`
241			`nop`
242			`nop`
243
244			`/*`
245			`* Restore the global registers we used`
246			`*/`
247
248			`mov %l3, %g1`
249			`mov %l4, %g2`
250			`mov %l5, %g3`
251			`mov %l6, %g4`
252			`mov %l7, %g5`
253
254			`jmpl %l2, %g0`
255			`rett %l2 + 4`
256
257			`/* end of file */`