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/src/microcode/cmpauxmd/alpha.m4

#
m4 | 414 lines | 159 code | 21 blank | 234 comment | 0 complexity | e51690aed641fd96c80821f669e6db5c MD5 | raw file
Possible License(s): GPL-2.0 
    

  1.  ### -*- Midas -*-
    2. 

  2.  ### 
    3. 

  3.  ### Copyright (C) 1992 Digital Equipment Corporation (D.E.C.)
    4. 

  4.  ### Copyright (C) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993,
    5. 

  5.  ###     1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003,
    6. 

  6.  ###     2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013,
    7. 

  7.  ###     2014 Massachusetts Institute of Technology
    8. 

  8.  ### 
    9. 

  9.  ### This software was developed at the Digital Equipment Corporation
    10. 

  10.  ### Cambridge Research Laboratory.  Permission to copy this software, to
    11. 

  11.  ### redistribute it, and to use it for any purpose is granted, subject to
    12. 

  12.  ### the following restrictions and understandings.
    13. 

  13.  ### 
    14. 

  14.  ### 1. Any copy made of this software must include this copyright notice
    15. 

  15.  ### in full.
    16. 

  16.  ### 
    17. 

  17.  ### 2. Users of this software agree to make their best efforts (a) to
    18. 

  18.  ### return to both the Digital Equipment Corporation Cambridge Research
    19. 

  19.  ### Lab (CRL) and the MIT Scheme project any improvements or extensions
    20. 

  20.  ### that they make, so that these may be included in future releases; and
    21. 

  21.  ### (b) to inform CRL and MIT of noteworthy uses of this software.
    22. 

  22.  ### 
    23. 

  23.  ### 3. All materials developed as a consequence of the use of this
    24. 

  24.  ### software shall duly acknowledge such use, in accordance with the usual
    25. 

  25.  ### standards of acknowledging credit in academic research.
    26. 

  26.  ### 
    27. 

  27.  ### 4. D.E.C. has made no warrantee or representation that the operation
    28. 

  28.  ### of this software will be error-free, and D.E.C. is under no obligation
    29. 

  29.  ### to provide any services, by way of maintenance, update, or otherwise.
    30. 

  30.  ### 
    31. 

  31.  ### 5. In conjunction with products arising from the use of this material,
    32. 

  32.  ### there shall be no use of the name of the Digital Equipment Corporation
    33. 

  33.  ### nor of any adaptation thereof in any advertising, promotional, or
    34. 

  34.  ### sales literature without prior written consent from D.E.C. in each
    35. 

  35.  ### case.
    36. 

  36. 
    37. 

  37.  ### Alpha Architecture assembly language part of the compiled
    38. 

  38.  ### code interface. See cmpint.txt, cmpint.c, cmpint-alpha.h, and
    39. 

  39.  ### cmpgc.h for more documentation.
    40. 

  40.  ###
    41. 

  41.  ### NOTE:
    42. 

  42.  ###	Assumptions:
    43. 

  43.  ###
    44. 

  44.  ###	1) The C compiler divides registers into three groups:
    45. 

  45.  ###	- Linkage registers, used for procedure calls and global
    46. 

  46.  ###	references.  On Alpha: 26 (return address), 27 (procedure
    47. 

  47.  ###	descriptor), 28 (assembler temp), 29 (global pointer),
    48. 

  48.  ###	30 (stack pointer), and 31 (always 0).
    49. 

  49.  ###	- super temporaries, not preserved accross procedure calls and
    50. 

  50.  ###	always usable. On Alpha: 0-8, 16-21 (argument registers), and
    51. 

  51.  ###	22-25.  Values are returned in 0.
    52. 

  52.  ###	- preserved registers saved by the callee if they are written.
    53. 

  53.  ###	On Alpha: 9-14, 15 (frame base)
    54. 

  54.  ###
    55. 

  55.  ###	2) Arguments, if passed on a stack, are popped by the caller.
    56. 

  56.  ###	Thus most "leaf" procedures need not worry about them. On
    57. 

  57.  ###	Alpha: The first six arguments are passed in registers and
    58. 

  58.  ###	have no space allocated on the stack.  Integer scalars are
    59. 

  59.  ###	returned in register 0; floating point scalars are returned
    60. 

  60.  ###	in fp0; floating point complex numbers are returned in fp0 and
    61. 

  61.  ###	fp1; structured values are returned through a pointer passed
    62. 

  62.  ###	in the first argument register and the remaining arguments are
    63. 

  63.  ###	shifted over by one register.
    64. 

  64.  ###
    65. 

  65.  ###	3) There is a hardware or software maintained stack for
    66. 

  66.  ###	control.  The procedure calling sequence may leave return
    67. 

  67.  ###	addresses in registers, but they must be saved somewhere for
    68. 

  68.  ###	nested calls and recursive procedures.  On Alpha: Passed in a
    69. 

  69.  ###	register, and no slot stack exists.  The return link is in 26.
    70. 

  70.  ###	The (C) stack pointer is in 30.
    71. 

  71.  ###
    72. 

  72.  ###	4) C procedures return long values in a super temporary
    73. 

  73.  ###	register.  Alpha: two or more word structures are returned in
    74. 

  74.  ###	a location specified by the contents of the first argument
    75. 

  75.  ###	register, and all other arguments are shifted over one
    76. 

  76.  ###	location (i.e.  apparent argument 1 is passed in the register
    77. 

  77.  ###	usually used for argument 2, etc.)
    78. 

  78.  ###
    79. 

  79.  ###	5) On Alpha we don't know the floating point register save
    80. 

  80.  ###	convention yet.
    81. 

  81.  ###
    82. 

  82.  ### Compiled Scheme code uses the following register convention.
    83. 

  83.  ### Note that scheme_to_interface, the register block, the closure
    84. 

  84.  ### hook, link_to_interface, compiled_entry_type_bits, and
    85. 

  85.  ### closure_free are preserved by C calls, but the others are not,
    86. 

  86.  ### since they change dynamically.  trampoline_to_interface can be
    87. 

  87.  ### reached at a fixed offset from scheme_to_interface.
    88. 

  88.  ###
    89. 

  89.  ### Register Usage Information
    90. 

  90.  ### Number  .dis   C                 Scheme
    91. 

  91.  ### ======  ====   =======           ======
    92. 

  92.  ### 0       v0     Return Value      Return Value
    93. 

  93.  ### 1       t0     caller saves      <free, but utility index (not shifted)>
    94. 

  94.  ### 2       t1     caller saves      Stack-Pointer
    95. 

  95.  ### 3       t2     caller saves      MemTop
    96. 

  96.  ### 4       t3     caller saves      Free
    97. 

  97.  ### 5       t4     caller saves      Dynamic Link
    98. 

  98.  ### 6       t5     caller saves      <free>
    99. 

  99.  ### 7       t6     caller saves      <free>
    100. 

  100.  ### 8       t7     caller saves      <free>
    101. 

  101.  ### 9       s0     callee saves      Regs-Pointer
    102. 

  102.  ### 10      s1     callee saves      Scheme-To-Interface
    103. 

  103.  ### 11      s2     callee saves      Closure Hook (jump ind. for full addr.)
    104. 

  104.  ### 12      s3     callee saves      Link-To-Interface
    105. 

  105.  ### 13      s4     callee saves      Compiled-Entry-Type-Bits
    106. 

  106.  ### 14      s5     callee saves      Closure-Free
    107. 

  107.  ### 15      fp?    frame base        <free>
    108. 

  108.  ### 16      a0     argument 1        <free, but for utilities>
    109. 

  109.  ### 17      a1     argument 2        <free, but for utilities>
    110. 

  110.  ### 18      a2     argument 3        <free, but for utilities>
    111. 

  111.  ### 19      a3     argument 4        <free, but for utilities>
    112. 

  112.  ### 20      a4     argument 5        <free, but for utilities>
    113. 

  113.  ### 21      a5     argument 6        <free>
    114. 

  114.  ### 22      t8     caller saves      <free>
    115. 

  115.  ### 23      t9     caller saves      <free>
    116. 

  116.  ### 24      t10    caller saves      <free>
    117. 

  117.  ### 25      t11    caller saves      <free>
    118. 

  118.  ### 26      ra     return address    <free, but used for closure linkage>
    119. 

  119.  ### 27      t12    proc. descript.   <free>
    120. 

  120.  ### 28      at?    volatile scratch  Assembler Temporary (tensioning)
    121. 

  121.  ### 29      gp     global pointer    <free>
    122. 

  122.  ### 30      sp     stack pointer     C Stack Pointer (do not use!)
    123. 

  123.  ### 31      zero   Z E R O           Z E R O
    124. 

  124. 

  125.  # The following are derived from cmpint-alpha.h, scaled by 8
    126. 

  126. #define REGBLOCK_FIRST_EXTRA			128
    127. 

  127. #define REGBLOCK_ADDRESS_OF_STACK_POINTER	REGBLOCK_FIRST_EXTRA
    128. 

  128. #define REGBLOCK_ADDRESS_OF_FREE		REGBLOCK_FIRST_EXTRA+8
    129. 

  129. #define REGBLOCK_ADDRESS_OF_UTILITY_TABLE	REGBLOCK_FIRST_EXTRA+16
    130. 

  130. #define REGBLOCK_ALLOCATE_CLOSURE		REGBLOCK_FIRST_EXTRA+24
    131. 

  131. 

  132.  # The following are derived from const.h, scaled by 8
    133. 

  133. #define REGBLOCK_MEMTOP			0
    134. 

  134. #define REGBLOCK_STACKGUARD		8
    135. 

  135. #define REGBLOCK_VAL			16
    136. 

  136. #define REGBLOCK_ENV			24
    137. 

  137. #define REGBLOCK_COMPILER_TEMP		32
    138. 

  138. #define REGBLOCK_EXPR			40
    139. 

  139. #define REGBLOCK_RETURN			48
    140. 

  140. #define REGBLOCK_LEXPR_ACTUALS		56
    141. 

  141. #define REGBLOCK_PRIMITIVE		64
    142. 

  142. #define REGBLOCK_CLOSURE_FREE		72
    143. 

  143. #define REGBLOCK_CLOSURE_SPACE		80
    144. 

  144. 

  145. #include "types.h"
    146. 

  146. #include <machine/pal.h>
    147. 

  147. 	.text	
    148. 

  148. 	.set	noat
    149. 

  149. 	.set	noreorder
    150. 

  150. 	.set	nomacro
    151. 

  151. 

  152.  ###	A bunch of .aent pseudo-ops were removed because they generate
    153. 

  153.  ###	a NOP, and we are counting instructions
    154. 

  154. 

  155.  #      .align 16 
    156. 

  156.  # ^ Apparently the assembler does not like that, but will take the following.
    157. 

  157.  # Even though the manual says 1-4 is the valid range.
    158. 

  158. 

  159. 	.align 12
    160. 

  160. 	.ent hook_jump_table 0
    161. 

  161. 	.globl	hook_jump_table
    162. 

  162. hook_jump_table:
    163. 

  163. 	# All entries in this table must be exactly four
    164. 

  164. 	# instructions long (see lapgen.scm)
    165. 

  165. 

  166.  ###	.aent	scheme_closure_hook
    167. 

  167. 	.globl	scheme_closure_hook
    168. 

  168. scheme_closure_hook:	# Entry 0, Offset 0
    169. 

  169. 	# Compiled code in a closure can be of the form
    170. 

  170. 	#	JMP $26,($11),0
    171. 

  171. 	#	<desired address>
    172. 

  172. 	# when <desired address> is too far away, and $11
    173. 

  173. 	# points here.
    174. 

  174. 	ldq	$22,0($26)
    175. 

  175. 	jmp	$28,($22),0
    176. 

  176. 	nop
    177. 

  177. 	nop
    178. 

  178. 

  179.  ###	.aent	asm_allocate_closure
    180. 

  180. asm_allocate_closure:	# Entry 1, Offset 16
    181. 

  181. 	# This must preserve ALL Scheme allocatable registers
    182. 

  182. 	# $16 has the total number of Scheme objects to allocate
    183. 

  183.         # $17 has pointer to the first entry point, 16 bytes into the
    184. 

  184.         #     block we failed to allocate.
    185. 

  185. 	# $28 has the return address
    186. 

  186. 	# Returns an offset 16 bytes into the allocated space in $17
    187. 

  187. 	# It fills the allocated region with 
    188. 

  188.         #       SUBQ SP,#8,SP//JMP $26,($11),hint
    189. 

  189. 	# and then synchronizes the I- and D-caches for this region of
    190. 

  190.         # memory.  It also needs to update regnum:closure-free and
    191. 

  191.         # free (i.e. registers $14 and $4)
    192. 

  192. 

  193. 	stq	$0,80($sp)
    194. 

  194. 	stq	$1,88($sp)
    195. 

  195. 	ldq	$1,REGBLOCK_ADDRESS_OF_FREE($9)
    196. 

  196. 	br	$31,asm_allocate_continue
    197. 

  197. 

  198. asm_allocate_continue:
    199. 

  199. 	stq	$2,96($sp)
    200. 

  200. 	# Register 3 is MemTop
    201. 

  201. 	stq	$4,0($1)	# Store into Free itself
    202. 

  202. 	stq	$5,104($sp)
    203. 

  203. 	stq	$6,112($sp)
    204. 

  204. 	stq	$7,120($sp)
    205. 

  205. 	stq	$8,128($sp)
    206. 

  206. 	# 9 - 15 are callee saves anyway
    207. 

  207. 	# 16 and 17 are the argument registers we are passing through
    208. 

  208. 	stq	$18,136($sp)
    209. 

  209. 	stq	$19,144($sp)
    210. 

  210. 	stq	$20,152($sp)
    211. 

  211. 	stq	$21,160($sp)
    212. 

  212. 	stq	$22,168($sp)
    213. 

  213. 	stq	$23,176($sp)
    214. 

  214. 	stq	$24,184($sp)
    215. 

  215. 	stq	$25,192($sp)
    216. 

  216. 	stq	$26,200($sp)
    217. 

  217. 	stq	$27,208($sp)
    218. 

  218. 	stq	$28,216($sp)
    219. 

  219. 	stq	$29,224($sp)
    220. 

  220. 	# 30 is the stack pointer itself, 31 is ZERO
    221. 

  221. 	ldq	$27,REGBLOCK_ALLOCATE_CLOSURE($9)	
    222. 

  222. 	jsr	$26,($27),allocate_closure
    223. 

  223. 	ldq	$29,REGBLOCK_ADDRESS_OF_FREE($9)
    224. 

  224. 	bis	$0,$0,$17	# Return the value in $17
    225. 

  225. 	ldq	$0,80($sp)
    226. 

  226. 	ldq	$1,88($sp)
    227. 

  227. 	ldq	$2,96($sp)
    228. 

  228. 	ldq	$3,REGBLOCK_MEMTOP($9)
    229. 

  229. 	ldq	$4,0($29)	# Retrieve from Free itself
    230. 

  230. 	ldq	$5,104($sp)
    231. 

  231. 	ldq	$6,112($sp)
    232. 

  232. 	ldq	$7,120($sp)
    233. 

  233. 	ldq	$8,128($sp)
    234. 

  234. 	ldq	$14,REGBLOCK_CLOSURE_FREE($9)
    235. 

  235. 	ldq	$18,136($sp)
    236. 

  236. 	ldq	$19,144($sp)
    237. 

  237. 	ldq	$20,152($sp)
    238. 

  238. 	ldq	$21,160($sp)
    239. 

  239. 	ldq	$22,168($sp)
    240. 

  240. 	ldq	$23,176($sp)
    241. 

  241. 	ldq	$24,184($sp)
    242. 

  242. 	ldq	$25,192($sp)
    243. 

  243. 	ldq	$26,200($sp)
    244. 

  244. 	ldq	$27,208($sp)
    245. 

  245. 	ldq	$28,216($sp)
    246. 

  246. 	ldq	$29,224($sp)
    247. 

  247. 	ret	$28,($28),1
    248. 

  248. 	.end hook_jump_table
    249. 

  249. 

  250. 	.align 4
    251. 

  251. 	.globl	Flush_I_Cache
    252. 

  252. 	.ent Flush_I_Cache 0
    253. 

  253. Flush_I_Cache:
    254. 

  254. 	call_pal	PAL_imb
    255. 

  255. 	ret	$28,($26),1
    256. 

  256. 	.end	Flush_I_Cache
    257. 

  257. 
    258. 

  258.  # Argument (in $a0) is a compiled Scheme entry point
    259. 

  259.  # but save C registers first
    260. 

  260.  #
    261. 

  261.  # Frame layout:
    262. 

  262. #define FRAME_SIZE	232
    263. 

  263.  #     ....................
    264. 

  264.  # FS  .                  . <-- Old SP (not our property)
    265. 

  265.  #     ....................
    266. 

  266.  #FS-8 . Register save    .
    267. 

  267.  #     . area used by     .
    268. 

  268.  #  80 . Allocate_Closure .
    269. 

  269.  #     ....................
    270. 

  270.  #  72 . Return str. high .
    271. 

  271.  #     ....................
    272. 

  272.  #  64 . Return str. low  .
    273. 

  273.  #     ....................
    274. 

  274.  #  56 . Caller's $9 (S0) .
    275. 

  275.  #     ....................
    276. 

  276.  #  48 . Caller's $10 (S1).
    277. 

  277.  #     ....................
    278. 

  278.  #  40 . Caller's $11 (S2).
    279. 

  279.  #     ....................
    280. 

  280.  #  32 . Caller's $12 (S3).
    281. 

  281.  #     ....................
    282. 

  282.  #  24 . Caller's $13 (S4).
    283. 

  283.  #     ....................
    284. 

  284.  #  16 . Caller's $14 (S5).
    285. 

  285.  #     ....................
    286. 

  286.  #  8  . Caller's $15 (FP).
    287. 

  287.  #     ....................
    288. 

  288.  #  0  . Our return addr. . <-- New SP
    289. 

  289.  #     ....................
    290. 

  290. 

  291.  # IMPORTANT: If the following sequence is changed,
    292. 

  292.  # link_to_interface must remain aligned!
    293. 

  293. 

  294. 	.align	4
    295. 

  295. 	.globl	C_to_interface
    296. 

  296. 	.ent	C_to_interface 1
    297. 

  297. C_to_interface:
    298. 

  298. 	.set	macro
    299. 

  299. 	ldgp	$gp,0($27)	# Offset 0, 4
    300. 

  300. 	# which expands into (low and high from linker):
    301. 

  301. 	# ldah	$gp,high($t12)
    302. 

  302. 	# lda   $gp,low($gp)
    303. 

  303. 	.set	nomacro
    304. 

  304. 	lda	$sp,-FRAME_SIZE($sp)
    305. 

  305. 				# Offset 8: Allocate frame
    306. 

  306. 	stq	$9,56($sp)	# Offset 12
    307. 

  307. 	stq	$10,48($sp)	# Offset 16
    308. 

  308. 	stq	$11,40($sp)	# Offset 20
    309. 

  309. 	stq	$12,32($sp)	# Offset 24
    310. 

  310. 	stq	$13,24($sp)	# Offset 28
    311. 

  311. 	stq	$14,16($sp)	# Offset 32
    312. 

  312. 	stq	$15,8($sp)	# Offset 36
    313. 

  313. 	stq	$26,0($sp)	# Offset 40
    314. 

  314. 	.mask	0x0400fe00, -FRAME_SIZE
    315. 

  315. 	.frame	$sp,FRAME_SIZE,$26
    316. 

  316. 	br	$12,setup_registers_continue
    317. 

  317. 				# Offset 44
    318. 

  318. 

  319. #define LINK_TO_SCHEME 16
    320. 

  320. 

  321.  # IMPORTANT: The distance between link_to_interface
    322. 

  322.  # and scheme_to_interface is fixed at LINK_TO_SCHEME bytes!
    323. 

  323. 

  324.  ###	.aent	link_to_interface
    325. 

  325. link_to_interface:		# Offset 48, SHOULD BE octabyte aligned
    326. 

  326. 	# $1 has utility index
    327. 

  327. 	# $17 (arg 1) has return address from JMP that got you here
    328. 

  328. 	# $18 etc. have other utility arguments if needed
    329. 

  329. 	lda	$17,4($17)	# Skip over format word ...
    330. 

  330. 	br	$28,scheme_to_interface
    331. 

  331. 	nop
    332. 

  332. 	nop	
    333. 

  333. 

  334. 	.align 4
    335. 

  335.  ###	.aent 	scheme_to_interface
    336. 

  336. 	.globl 	scheme_to_interface
    337. 

  337. scheme_to_interface:
    338. 

  338. 	# $1 has utility index (not shifted)
    339. 

  339. 	# $17 (etc.) have utility arguments as needed
    340. 

  340. 	ldq	$24,REGBLOCK_ADDRESS_OF_UTILITY_TABLE($9)	# 0
    341. 

  341. 	stq	$0,REGBLOCK_VAL($9)				# 4
    342. 

  342. 	ldq	$22,REGBLOCK_ADDRESS_OF_STACK_POINTER($9)	# 8
    343. 

  343. 	ldq	$23,REGBLOCK_ADDRESS_OF_FREE($9)		# 12
    344. 

  344. 	stq	$14,REGBLOCK_CLOSURE_FREE($9)
    345. 

  345. 	s8addq	$1,$24,$24	# Address of entry in table	# 16
    346. 

  346. 	stq	$2,0($22)	# Save sp_register		# 20
    347. 

  347. 	ldq	$27,0($24)	# Destination address		# 24
    348. 

  348. 	lda	$16,64($sp)	# Return structure value here	# 28
    349. 

  349. 	stq	$4,0($23)	# Save Free			# 32
    350. 

  350. 	jsr	$26,($27),comutil_operator_arity_trap
    351. 

  351. 	ldq	$22,64($sp)	# Get next procedure address	# 40
    352. 

  352. 	ldq	$16,72($sp)	# Value to pass to next procedure	# 44
    353. 

  353. 	jmp	$28,($22),interface_to_scheme			# 48
    354. 

  354. 

  355.  # Argument (in $a0) is a compiled Scheme entry point.  Reload
    356. 

  356.  # the Scheme registers and go to work...any registers not reloaded
    357. 

  357.  # here must be callee saves by C.
    358. 

  358. 

  359. 	.align 4
    360. 

  360.  ###	.aent	interface_to_scheme
    361. 

  361. 	.globl	interface_to_scheme
    362. 

  362. interface_to_scheme:
    363. 

  363. 	ldq	$0,REGBLOCK_VAL($9)				# 64
    364. 

  364. 	# Register 1 isn't used
    365. 

  365. 	ldq	$2,REGBLOCK_ADDRESS_OF_STACK_POINTER($9)
    366. 

  366. 	ldq	$3,REGBLOCK_MEMTOP($9)
    367. 

  367. 	ldq	$4,REGBLOCK_ADDRESS_OF_FREE($9)
    368. 

  368. 	ldq	$2,0($2)
    369. 

  369. 	ldq	$4,0($4)
    370. 

  370. 	zap	$0,0x80,$5	# Initialize dynamic link register
    371. 

  371. 	.aent	off_to_scheme_code
    372. 

  372. 	.globl	off_to_scheme_code
    373. 

  373. off_to_scheme_code:
    374. 

  374. 	jmp	$28,($16),0	# Off to compiled code ...
    375. 

  375. 

  376. 	.align 4
    377. 

  377. setup_registers_continue:
    378. 

  378. 	.set	at
    379. 

  379. 	.set	macro
    380. 

  380. 	lda	$9,Registers
    381. 

  381.  #	lda	$10,scheme_to_interface-link_to_interface($12)
    382. 

  382.  #	^ The assembler cannot handle the instruction above.
    383. 

  383.  #	The offset is computed by counting the distance between
    384. 

  384.  #	both labels.
    385. 

  385. 	lda	$10,LINK_TO_SCHEME($12)
    386. 

  386.  #	lda	$11,scheme_closure_hook-link_to_interface($12)
    387. 

  387.  #	^ The assembler cannot handle the instruction above.
    388. 

  388.  #	use a more expensive 2-instruction sequence.
    389. 

  389. 	lda	$11,scheme_closure_hook
    390. 

  390. 	.set	nomacro
    391. 

  391. 	.set	noat
    392. 

  392. 	# Register 12 already initialized
    393. 

  393. 	bis	$31,TC_COMPILED_ENTRY,$13
    394. 

  394. 	sll	$13,56,$13	# Shift to most significant byte
    395. 

  395. 	ldq	$14,REGBLOCK_CLOSURE_FREE($9)
    396. 

  396. 	br	$28,interface_to_scheme
    397. 

  397. 

  398. 	.align 4
    399. 

  399. 	.aent	interface_to_C
    400. 

  400. 	.globl	interface_to_C
    401. 

  401. interface_to_C:
    402. 

  402.  # Argument 1 (in $16) is the returned value
    403. 

  403. 	bis	$16,$16,$0	# Real return value register
    404. 

  404. 	ldq	$26,0($sp)	# Return address
    405. 

  405. 	ldq	$9,56($sp)
    406. 

  406. 	ldq	$10,48($sp)
    407. 

  407. 	ldq	$11,40($sp)
    408. 

  408. 	ldq	$12,32($sp)
    409. 

  409. 	ldq	$13,24($sp)
    410. 

  410. 	ldq	$14,16($sp)
    411. 

  411. 	ldq	$15,8($sp)
    412. 

  412. 	lda	$sp,FRAME_SIZE($sp)
    413. 

  413. 	ret	$28,($26), 1
    414. 

  414. 	.end	C_to_interface
    415. 

  415.