mirror of
https://github.com/autc04/Retro68.git
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44 lines
1.4 KiB
Go
44 lines
1.4 KiB
Go
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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build mips64 mips64le
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package runtime
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import "unsafe"
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// adjust Gobuf as if it executed a call to fn with context ctxt
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// and then did an immediate Gosave.
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func gostartcall(buf *gobuf, fn, ctxt unsafe.Pointer) {
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if buf.lr != 0 {
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throw("invalid use of gostartcall")
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}
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buf.lr = buf.pc
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buf.pc = uintptr(fn)
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buf.ctxt = ctxt
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}
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// Called to rewind context saved during morestack back to beginning of function.
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// To help us, the linker emits a jmp back to the beginning right after the
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// call to morestack. We just have to decode and apply that jump.
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func rewindmorestack(buf *gobuf) {
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var inst uint32
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if buf.pc&3 == 0 && buf.pc != 0 {
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inst = *(*uint32)(unsafe.Pointer(buf.pc))
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if inst>>26 == 2 { // JMP addr
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//print("runtime: rewind pc=", hex(buf.pc), " to pc=", hex(buf.pc &^ uintptr(1<<28-1) | uintptr((inst&^0xfc000000)<<2)), "\n");
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buf.pc &^= 1<<28 - 1
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buf.pc |= uintptr((inst &^ 0xfc000000) << 2)
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return
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}
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if inst>>16 == 0x1000 { // BEQ R0, R0, offset
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//print("runtime: rewind pc=", hex(buf.pc), " to pc=", hex(buf.pc + uintptr(int32(int16(inst&0xffff))<<2 + 4)), "\n");
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buf.pc += uintptr(int32(int16(inst&0xffff))<<2 + 4)
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return
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}
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}
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print("runtime: pc=", hex(buf.pc), " ", hex(inst), "\n")
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throw("runtime: misuse of rewindmorestack")
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}
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