mirror of
https://github.com/bsnes-emu/bsnes.git
synced 2025-04-02 10:42:14 -04:00
81f43a4d01
This represents a major code restructuring. The dot-based and scanline-based renderers are now split into two separate core libraries, asnes and bsnes. For now at least, these are -internal- names. I'm not entirely decided on how I'm going to handle releasing these two separate builds. Regardless, the folders need names. asnes has had all of the processor subfolders collapsed back into their parent folders. In other words, ppu's functions were moved into ppu/sppu, and then ppu was deleted, and then ppu/sppu became the new ppu. Repeat this for the cpu, smp and dsp and there you go. asnes/dsp also removed the DSP_STATE_MACHINE option. This was done for the sake of consistency with the rest of the core. asnes' debugger mode is currently extremely broken, but I will be fixing it in time. And for now, bsnes has kept the processor abstraction layer. I may keep it around, not sure yet. It doesn't hurt speed or anything, so I'm not too worried about making a decision right away. I may throw snesfilter, snesreader and supergameboy into this folder, just to have everything in one place. The alternate GUI forks are definitely going in there as dotnet, cocoa and python. Compiled output goes to the out/ folder now, to prevent conflicts with a file and folder named bsnes, for instance.
325 lines
10 KiB
C
325 lines
10 KiB
C
/*
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* libco.ppc-elf
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* author: Kernigh
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* license: public domain
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*
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* PowerPC 32-bit ELF implementation of libco (for compile with GCC),
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* ported from PowerPC Mac OS X implementation (ppc.s) by Vas Crabb.
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* This ELF version works for OpenBSD, and might also work for FreeBSD,
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* NetBSD and Linux.
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*
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* Note 1: This implementation does not handle the AltiVec/VMX
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* registers, because the ELF ABI does not mention them,
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* and my OpenBSD system is not using them.
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*
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* Note 2: If you want position-independent code, then you must
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* define __PIC__. gcc -fpic or -fPIC defines __PIC__, but
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* gcc -fpie or -fPIE might not. If you want to use -fpie
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* or -fPIE, then you might need a manual definition:
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* gcc -fpie -D__PIC__=1
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* gcc -fPIE -D__PIC__=2
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*
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* The ELF ABI is "System V Application Binary Interface, PowerPC
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* Processor Supplement", which you can get from
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* <http://refspecs.linux-foundation.org/elf/elfspec_ppc.pdf>
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* (PDF file, hosted by Linux Foundation).
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*
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* ELF and Mac OS X use similar conventions to allocate the registers,
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* and to pass arguments and return values through registers. The main
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* differences are that ELF has a slightly different stack format, that
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* symbols are different (and without an extra underscore at the start),
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* and that the assembly syntax is different.
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*
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* A function may destroy the values of volatile registers, but must
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* preserve the values of nonvolatile registers. So the co_switch()
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* function only saves the nonvolatile registers.
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*
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* [nonvolatile registers in ELF]
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* %r1, %r14..%r31
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* %f14..%f31
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* %cr2..%cr4 in cr
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*
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* [volatile registers in ELF]
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* %r0, %r3..%r10
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* %f0..%f13
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* %cr0, %cr1, %cr5..%cr7 in cr
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* ctr, lr, xer
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*
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* lr (link register) is volatile, but it contains the return address,
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* so co_switch must save lr.
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*
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* %r13 is the small data pointer. This is constant across threads, so
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* co_switch() does not touch %r13.
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*
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* %r2 is a reserved register, so co_switch() does not touch %r2. Some
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* systems might borrow an idea from the PowerPC Embedded ABI, and might
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* use %r2 as a small read-only data pointer, which is constant across
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* threads.
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*/
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#ifdef __cplusplus
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extern "C" {
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#endif
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typedef void * cothread_t;
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/*
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* co_active_context is either in a global offset table (if we are
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* compiling -fPIC or -fPIE) or has an absolute position.
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*/
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static void *co_main_stack_pointer;
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static cothread_t co_active_context = &co_main_stack_pointer;
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extern cothread_t co_active() {
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return co_active_context;
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}
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/*
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* Embedded assembly.
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*
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* We are not using the percent-sign substitution feature,
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* so we must write "%r1", not "%%r1".
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*
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* We always write 'bl malloc@plt', not 'bl malloc'. The '@plt'
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* is necessary in position-indepent code and seems to have no
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* significant effect in fixed-position code.
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*
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* We never use the 'lmw' or 'stmw' instructions. The ELF ABI
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* mentions that these instructions "are usually slower than
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* a sequence of other instructions that have the same effect."
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* We instead use sequences of 'lwz' or 'stz' instructions.
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*/
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__asm__("\n"
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"### embedded assembly \n"
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".section \".text\" \n"
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" .balign 4 \n"
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" \n"
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/*
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* void co_switch(co_thread to %r3)
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*
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* Allocate our stack frame of 240 bytes:
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* Old New Value
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* 4(%r1) 244(%r1) return address, used by us
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* 0(%r1) 240(%r1) frame pointer
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* 232(%r1) %f31
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* 224(%r1) %f30
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* ...
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* 96(%r1) %f14
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* 92(%r1) %r31
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* 88(%r1) %r30
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* ...
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* 24(%r1) %r14
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* 20(%r1) condition register
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* 8(%r1) padding of 12 bytes
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* 4(%r1) return address, never used
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* 0(%r1) frame pointer
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*
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* Save our registers in our stack frame.
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* Save our stack pointer in 0(%r4).
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* Switch to the stack of the other thread.
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* Restore registers and return.
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*/
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" .globl co_switch \n"
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" .type co_switch, @function \n"
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"co_switch: \n"
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" mflr %r0 # %r0 = return address \n"
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" mfcr %r9 # %r9 = condition register \n"
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" stwu %r1, -240(%r1) # allocate stack frame \n"
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" \n"
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" stw %r0, 244(%r1) # save return address \n"
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" stfd %f31, 232(%r1) # save floating-point regs \n"
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" stfd %f30, 224(%r1) \n"
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" stfd %f29, 216(%r1) \n"
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" stfd %f28, 208(%r1) \n"
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" stfd %f27, 200(%r1) \n"
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" stfd %f26, 192(%r1) \n"
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" stfd %f25, 184(%r1) \n"
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" stfd %f24, 176(%r1) \n"
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" stfd %f23, 168(%r1) \n"
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" stfd %f22, 160(%r1) \n"
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" stfd %f21, 152(%r1) \n"
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" stfd %f20, 144(%r1) \n"
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" stfd %f19, 136(%r1) \n"
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" stfd %f18, 128(%r1) \n"
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" stfd %f17, 120(%r1) \n"
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" stfd %f16, 112(%r1) \n"
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" stfd %f16, 104(%r1) \n"
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" stfd %f14, 96(%r1) \n"
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" stw %r31, 92(%r1) # save general-purpose regs \n"
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" stw %r30, 88(%r1) \n"
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" stw %r29, 84(%r1) \n"
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" stw %r28, 80(%r1) \n"
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" stw %r27, 76(%r1) \n"
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" stw %r26, 72(%r1) \n"
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" stw %r25, 68(%r1) \n"
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" stw %r24, 64(%r1) \n"
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" stw %r23, 60(%r1) \n"
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" stw %r22, 56(%r1) \n"
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" stw %r21, 52(%r1) \n"
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" stw %r20, 48(%r1) \n"
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" stw %r19, 44(%r1) \n"
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" stw %r18, 40(%r1) \n"
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" stw %r17, 36(%r1) \n"
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" stw %r16, 32(%r1) \n"
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" stw %r15, 28(%r1) \n"
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" stw %r14, 24(%r1) \n"
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" stw %r9, 20(%r1) # save condition reg \n"
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" \n"
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" # save current context, set new context \n"
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" # %r4 = co_active_context \n"
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" # co_active_context = %r3 \n"
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#if __PIC__ == 2
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" # position-independent code, large model (-fPIC) \n"
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" bl _GLOBAL_OFFSET_TABLE_@local-4 \n"
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" mflr %r8 # %r8 = address of got \n"
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" addis %r7, %r8, co_active_context@got@ha \n"
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" lwz %r6, co_active_context@got@l(%r7) \n"
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" lwz %r4, 0(%r6) \n"
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" stw %r3, 0(%r6) \n"
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#elif __PIC__ == 1
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" # position-independent code, small model (-fpic) \n"
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" bl _GLOBAL_OFFSET_TABLE_@local-4 \n"
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" mflr %r8 # %r8 = address of got \n"
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" lwz %r7, co_active_context@got(%r8) \n"
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" lwz %r4, 0(%r7) \n"
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" stw %r3, 0(%r7) \n"
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#else
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" # fixed-position code \n"
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" lis %r8, co_active_context@ha \n"
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" lwz %r4, co_active_context@l(%r8) \n"
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" stw %r3, co_active_context@l(%r8) \n"
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#endif
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" \n"
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" # save current stack pointer \n"
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" stw %r1, 0(%r4) \n"
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" # get new stack pointer \n"
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" lwz %r1, 0(%r3) \n"
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" \n"
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" lwz %r0, 244(%r1) # get return address \n"
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" lfd %f31, 232(%r1) # restore floating-point regs \n"
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" lfd %f30, 224(%r1) \n"
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" lfd %f29, 216(%r1) \n"
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" lfd %f28, 208(%r1) \n"
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" lfd %f27, 200(%r1) \n"
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" lfd %f26, 192(%r1) \n"
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" lfd %f25, 184(%r1) \n"
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" lfd %f24, 176(%r1) \n"
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" lfd %f23, 168(%r1) \n"
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" lfd %f22, 160(%r1) \n"
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" lfd %f21, 152(%r1) \n"
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" lfd %f20, 144(%r1) \n"
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" lfd %f19, 136(%r1) \n"
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" lfd %f18, 128(%r1) \n"
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" lfd %f17, 120(%r1) \n"
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" lfd %f16, 112(%r1) \n"
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" lfd %f16, 104(%r1) \n"
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" lfd %f14, 96(%r1) \n"
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" lwz %r31, 92(%r1) # restore general-purpose regs \n"
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" lwz %r30, 88(%r1) \n"
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" lwz %r29, 84(%r1) \n"
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" lwz %r28, 80(%r1) \n"
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" lwz %r27, 76(%r1) \n"
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" lwz %r26, 72(%r1) \n"
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" lwz %r25, 68(%r1) \n"
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" lwz %r24, 64(%r1) \n"
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" lwz %r23, 60(%r1) \n"
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" lwz %r22, 56(%r1) \n"
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" lwz %r21, 52(%r1) \n"
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" lwz %r20, 48(%r1) \n"
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" lwz %r19, 44(%r1) \n"
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" lwz %r18, 40(%r1) \n"
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" lwz %r17, 36(%r1) \n"
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" lwz %r16, 32(%r1) \n"
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" lwz %r15, 28(%r1) \n"
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" lwz %r14, 24(%r1) \n"
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" lwz %r9, 20(%r1) # get condition reg \n"
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" \n"
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" addi %r1, %r1, 240 # free stack frame \n"
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" mtlr %r0 # restore return address \n"
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" mtcr %r9 # restore condition register \n"
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" blr # return \n"
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" .size co_switch, . - co_switch \n"
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" \n"
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/*
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* cothread_t %r3 co_create(unsigned int stack_size %r3,
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* void (*coentry %r4)())
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*
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* Allocate a new stack, such that when you co_switch to that
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* stack, then co_switch returns to coentry.
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*/
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" .globl co_create \n"
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" .type co_create, @function \n"
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"co_create: \n"
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" mflr %r0 # %r0 = return address \n"
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" stwu %r1, -16(%r1) # allocate my stack frame \n"
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" stw %r0, 20(%r1) # save return address \n"
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" stw %r31, 12(%r1) # save %r31 \n"
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" stw %r30, 8(%r1) # save %r30 \n"
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" \n"
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" mr %r30, %r3 # %r30 = stack_size \n"
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" mr %r31, %r4 # %r31 = coentry \n"
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" \n"
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" # Call malloc(stack_size %r3) to allocate stack; \n"
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" # malloc() probably uses good alignment. \n"
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" # \n"
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" bl malloc@plt # returns %r3 = low end \n"
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" cmpwi %r3, 0 # if returned NULL, \n"
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" beq- 1f # then abort \n"
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" \n"
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" # we return %r3 = low end of stack \n"
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" add %r4, %r3, %r30 # %r4 = high end of stack \n"
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" \n"
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" # uncomment if malloc() uses wrong alignment \n"
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" #rlwinm %r4,%r4,0,0,27 # force 16-byte alignment \n"
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" \n"
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/*
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* Allocate two stack frames:
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* 16 bytes for stack frame with return address
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* 240 bytes for co_switch stack frame
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*
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* Old New Value
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* -8(%r4) 248(%r5) padding of 8 bytes
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* -12(%r4) 244(%r5) return address = coentry
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* -16(%r4) 240(%r5) frame pointer = NULL
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* 232(%r5) %f31 = 0
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* ...
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* 20(%r5) condition register = 0
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* 0(%r5) frame pointer
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*/
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" li %r9, (240-20)/4+1 \n"
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" addi %r5, %r4, -16 # allocate first stack frame \n"
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" li %r0, 0 \n"
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" stwu %r5, -240(%r5) # allocate second stack frame \n"
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" li %r8, 20 \n"
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" mtctr %r9 # loop %r9 times \n"
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"2: # loop to store zero to 20(%r5) through 240(%r5) \n"
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" stwx %r0, %r5, %r8 \n"
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" addi %r8, %r8, 4 # index += 4 \n"
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" bdnz+ 2b # ctr -= 1, branch if nonzero \n"
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" \n"
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" stw %r31, 244(%r5) # return address = coentry \n"
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" stw %r5, 0(%r3) # save stack pointer \n"
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" \n"
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" lwz %r0, 20(%r1) # get return address \n"
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" lwz %r31, 12(%r1) # restore %r31 \n"
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" lwz %r30, 8(%r1) # restore %r30 \n"
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" mtlr %r0 # restore return address \n"
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" addi %r1, %r1, 16 # free stack frame \n"
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" blr # return \n"
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" \n"
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"1: b abort@plt # branch 1f to abort \n"
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" .size co_create, . - co_create \n"
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" \n"
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/*
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* void co_delete(cothread_t) => void free(void *)
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*/
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" .globl co_delete \n"
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" .type co_delete, @function \n"
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"co_delete: \n"
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" b free@plt \n"
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" \n"
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);
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#ifdef __cplusplus
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}
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#endif
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