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-/*
- * QuickThreads -- Threads-building toolkit.
- * Copyright (c) 1993 by David Keppel
- *
- * Permission to use, copy, modify and distribute this software and
- * its documentation for any purpose and without fee is hereby
- * granted, provided that the above copyright notice and this notice
- * appear in all copies. This software is provided as a
- * proof-of-concept and for demonstration purposes; there is no
- * representation about the suitability of this software for any
- * purpose.
- */
-
-#ifndef QT_KSR1_H
-#define QT_KSR1_H
-
-/*
- Stack layout:
-
- Registers are saved in strictly low to high order, FPU regs first
- (only if qt_block is called), CEU regs second, IPU regs next, with no
- padding between the groups.
-
- Callee-save: f16..f63; c15..c30; i12..i30.
- Args passed in i2..i5.
-
- Note: c31 is a private data pointer. It is not changed on thread
- swaps with the assumption that it represents per-processor rather
- than per-thread state.
-
- Note: i31 is an instruction count register that is updated by the
- context switch routines. Like c31, it is not changed on context
- switches.
-
- This is what we want on startup:
-
-
- +------ <-- BOS: Bottom of stack (grows down)
- | 80 (128 - 48) bytes of padding to a 128-byte boundary
- +---
- | only
- | userf
- | t
- | u
- | qt_start$TXT
- | (empty) <-- qt.sp
- +------ <-- (BOS - 128)
-
- This is why we want this on startup:
-
- A thread begins running when the restore procedure switches thread stacks
- and pops a return address off of the top of the new stack (see below
- for the reason why we explicitly store qt_start$TXT). The
- block procedure pushes two jump addresses on a thread's stack before
- it switches stacks. The first is the return address for the block
- procedure, and the second is a restore address. The return address
- is used to jump back to the thread that has been switched to; the
- restore address is a jump within the block code to restore the registers.
- Normally, this is just a jump to the next address. However, on thread
- startup, this is a jump to qt_start$TXT. (The block procedure stores
- the restore address at an offset of 8 bytes from the top of the stack,
- which is also the offset at which qt_start$TXT is stored on the stacks
- of new threads. Hence, when the block procedure switches to a new
- thread stack, it will initially jump to qt_start$TXT; thereafter,
- it jumps to the restore code.)
-
- qt_start$TXT, after it has read the initial data on the new thread's
- stack and placed it in registers, pops the initial stack frame
- and gives the thread the entire stack to use for execution.
-
- The KSR runtime system has an unusual treatment of pointers to
- functions. From C, taking the `name' of a function yields a
- pointer to a _constant block_ and *not* the address of the
- function. The zero'th entry in the constant block is a pointer to
- the function.
-
- We have to be careful: the restore procedure expects a return
- address on the top of the stack (pointed to by qt.sp). This is not
- a problem when restoring a thread that has run before, since the
- block routine would have stored the return address on top of the
- stack. However, when ``faking up'' a thread start (bootstrapping a
- thread stack frame), the top of the stack needs to contain a
- pointer to the code that will start the thread running.
-
- The pointer to the startup code is *not* `qt_start'. It is the
- word *pointed to* by `qt_start'. Thus, we dereference `qt_start',
- see QT_ARGS_MD below.
-
- On varargs startup (still unimplemented):
-
- | padding to 128 byte boundary
- | varargs <-- padded to a 128-byte-boundary
- +---
- | caller's frame, 16 bytes
- | 80 bytes of padding (frame padded to a 128-byte boundary)
- +---
- | cleanup
- | vuserf
- | startup
- | t
- +---
- | qt_start <-- qt.sp
- +---
-
- Of a suspended thread:
-
- +---
- | caller's frame, 16 bytes
- | fpu registers 47 regs * 8 bytes/reg 376 bytes
- | ceu registers 16 regs * 8 bytes/reg 128 bytes
- | ipu registers 19 regs * 8 bytes/reg 152 bytes
- | :
- | 80 bytes of padding
- | :
- | qt_restore <-- qt.sp
- +---
-
- */
-
-
-#define QT_STKALIGN 128
-#define QT_GROW_DOWN
-typedef unsigned long qt_word_t;
-
-#define QT_STKBASE QT_STKALIGN
-#define QT_VSTKBASE QT_STKBASE
-
-extern void qt_start(void);
-/*
- * See the discussion above for what indexing into a procedure ptr
- * does for us (it's lovely, though, isn't it?).
- *
- * This assumes that the address of a procedure's code is the
- * first word in a procedure's constant block. That's how the manual
- * says it will be arranged.
- */
-#define QT_ARGS_MD(sp) (QT_SPUT (sp, 1, ((qt_word_t *)qt_start)[0]))
-
-/*
- * The *index* (positive offset) of where to put each value.
- * See the picture of the stack above that explains the offsets.
- */
-#define QT_ONLY_INDEX (5)
-#define QT_USER_INDEX (4)
-#define QT_ARGT_INDEX (3)
-#define QT_ARGU_INDEX (2)
-
-#define QT_VARGS_DEFAULT
-#define QT_VARGS(sp, nb, vargs, pt, startup, vuserf, cleanup) \
- (qt_vargs (sp, nbytes, &vargs, pt, startup, vuserf, cleanup))
-
-
-#define QT_VARGS_MD0(sp, vabytes) \
- ((qt_t *)(((char *)(sp)) - 4*8 - QT_STKROUNDUP(vabytes)))
-
-extern void qt_vstart(void);
-#define QT_VARGS_MD1(sp) (QT_SPUT (sp, 0, ((qt_word_t *)qt_vstart)[0]))
-
-#define QT_VCLEANUP_INDEX (4)
-#define QT_VUSERF_INDEX (3)
-#define QT_VSTARTUP_INDEX (2)
-#define QT_VARGT_INDEX (1)
-
-#endif /* def QT_KSR1_H */