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Diffstat (limited to 'src/runtime/vlop_arm.s')
-rw-r--r-- | src/runtime/vlop_arm.s | 317 |
1 files changed, 317 insertions, 0 deletions
diff --git a/src/runtime/vlop_arm.s b/src/runtime/vlop_arm.s new file mode 100644 index 000000000..b4b905bb7 --- /dev/null +++ b/src/runtime/vlop_arm.s @@ -0,0 +1,317 @@ +// Inferno's libkern/vlop-arm.s +// http://code.google.com/p/inferno-os/source/browse/libkern/vlop-arm.s +// +// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved. +// Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com). All rights reserved. +// Portions Copyright 2009 The Go Authors. All rights reserved. +// +// Permission is hereby granted, free of charge, to any person obtaining a copy +// of this software and associated documentation files (the "Software"), to deal +// in the Software without restriction, including without limitation the rights +// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +// copies of the Software, and to permit persons to whom the Software is +// furnished to do so, subject to the following conditions: +// +// The above copyright notice and this permission notice shall be included in +// all copies or substantial portions of the Software. +// +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN +// THE SOFTWARE. + +#include "zasm_GOOS_GOARCH.h" +#include "textflag.h" + +arg=0 + +/* replaced use of R10 by R11 because the former can be the data segment base register */ + +TEXT _mulv(SB), NOSPLIT, $0 + MOVW l0+0(FP), R2 /* l0 */ + MOVW h0+4(FP), R11 /* h0 */ + MOVW l1+8(FP), R4 /* l1 */ + MOVW h1+12(FP), R5 /* h1 */ + MULLU R4, R2, (R7,R6) + MUL R11, R4, R8 + ADD R8, R7 + MUL R2, R5, R8 + ADD R8, R7 + MOVW R6, ret_lo+16(FP) + MOVW R7, ret_hi+20(FP) + RET + +// trampoline for _sfloat2. passes LR as arg0 and +// saves registers R0-R13 and CPSR on the stack. R0-R12 and CPSR flags can +// be changed by _sfloat2. +TEXT _sfloat(SB), NOSPLIT, $68-0 // 4 arg + 14*4 saved regs + cpsr + return value + MOVW R14, 4(R13) + MOVW R0, 8(R13) + MOVW $12(R13), R0 + MOVM.IA.W [R1-R12], (R0) + MOVW $72(R13), R1 // correct for frame size + MOVW R1, 60(R13) + WORD $0xe10f1000 // mrs r1, cpsr + MOVW R1, 64(R13) + // Disable preemption of this goroutine during _sfloat2 by + // m->locks++ and m->locks-- around the call. + // Rescheduling this goroutine may cause the loss of the + // contents of the software floating point registers in + // m->freghi, m->freglo, m->fflag, if the goroutine is moved + // to a different m or another goroutine runs on this m. + // Rescheduling at ordinary function calls is okay because + // all registers are caller save, but _sfloat2 and the things + // that it runs are simulating the execution of individual + // program instructions, and those instructions do not expect + // the floating point registers to be lost. + // An alternative would be to move the software floating point + // registers into G, but they do not need to be kept at the + // usual places a goroutine reschedules (at function calls), + // so it would be a waste of 132 bytes per G. + MOVW g_m(g), R8 + MOVW m_locks(R8), R1 + ADD $1, R1 + MOVW R1, m_locks(R8) + MOVW $1, R1 + MOVW R1, m_softfloat(R8) + BL runtime·_sfloat2(SB) + MOVW 68(R13), R0 + MOVW g_m(g), R8 + MOVW m_locks(R8), R1 + SUB $1, R1 + MOVW R1, m_locks(R8) + MOVW $0, R1 + MOVW R1, m_softfloat(R8) + MOVW R0, 0(R13) + MOVW 64(R13), R1 + WORD $0xe128f001 // msr cpsr_f, r1 + MOVW $12(R13), R0 + // Restore R1-R12, R0. + MOVM.IA.W (R0), [R1-R12] + MOVW 8(R13), R0 + RET + +// trampoline for _sfloat2 panic. +// _sfloat2 instructs _sfloat to return here. +// We need to push a fake saved LR onto the stack, +// load the signal fault address into LR, and jump +// to the real sigpanic. +// This simulates what sighandler does for a memory fault. +TEXT _sfloatpanic(SB),NOSPLIT,$-4 + MOVW $0, R0 + MOVW.W R0, -4(R13) + MOVW g_sigpc(g), LR + B runtime·sigpanic(SB) + +// func udiv(n, d uint32) (q, r uint32) +// Reference: +// Sloss, Andrew et. al; ARM System Developer's Guide: Designing and Optimizing System Software +// Morgan Kaufmann; 1 edition (April 8, 2004), ISBN 978-1558608740 +q = 0 // input d, output q +r = 1 // input n, output r +s = 2 // three temporary variables +M = 3 +a = 11 +// Be careful: R(a) == R11 will be used by the linker for synthesized instructions. +TEXT udiv<>(SB),NOSPLIT,$-4 + CLZ R(q), R(s) // find normalizing shift + MOVW.S R(q)<<R(s), R(a) + MOVW $fast_udiv_tab<>-64(SB), R(M) + ADD.NE R(a)>>25, R(M), R(a) // index by most significant 7 bits of divisor + MOVBU.NE (R(a)), R(a) + + SUB.S $7, R(s) + RSB $0, R(q), R(M) // M = -q + MOVW.PL R(a)<<R(s), R(q) + + // 1st Newton iteration + MUL.PL R(M), R(q), R(a) // a = -q*d + BMI udiv_by_large_d + MULAWT R(a), R(q), R(q), R(q) // q approx q-(q*q*d>>32) + TEQ R(M)->1, R(M) // check for d=0 or d=1 + + // 2nd Newton iteration + MUL.NE R(M), R(q), R(a) + MOVW.NE $0, R(s) + MULAL.NE R(q), R(a), (R(q),R(s)) + BEQ udiv_by_0_or_1 + + // q now accurate enough for a remainder r, 0<=r<3*d + MULLU R(q), R(r), (R(q),R(s)) // q = (r * q) >> 32 + ADD R(M), R(r), R(r) // r = n - d + MULA R(M), R(q), R(r), R(r) // r = n - (q+1)*d + + // since 0 <= n-q*d < 3*d; thus -d <= r < 2*d + CMN R(M), R(r) // t = r-d + SUB.CS R(M), R(r), R(r) // if (t<-d || t>=0) r=r+d + ADD.CC $1, R(q) + ADD.PL R(M)<<1, R(r) + ADD.PL $2, R(q) + RET + +udiv_by_large_d: + // at this point we know d>=2^(31-6)=2^25 + SUB $4, R(a), R(a) + RSB $0, R(s), R(s) + MOVW R(a)>>R(s), R(q) + MULLU R(q), R(r), (R(q),R(s)) + MULA R(M), R(q), R(r), R(r) + + // q now accurate enough for a remainder r, 0<=r<4*d + CMN R(r)>>1, R(M) // if(r/2 >= d) + ADD.CS R(M)<<1, R(r) + ADD.CS $2, R(q) + CMN R(r), R(M) + ADD.CS R(M), R(r) + ADD.CS $1, R(q) + RET + +udiv_by_0_or_1: + // carry set if d==1, carry clear if d==0 + BCC udiv_by_0 + MOVW R(r), R(q) + MOVW $0, R(r) + RET + +udiv_by_0: + // The ARM toolchain expects it can emit references to DIV and MOD + // instructions. The linker rewrites each pseudo-instruction into + // a sequence that pushes two values onto the stack and then calls + // _divu, _modu, _div, or _mod (below), all of which have a 16-byte + // frame plus the saved LR. The traceback routine knows the expanded + // stack frame size at the pseudo-instruction call site, but it + // doesn't know that the frame has a non-standard layout. In particular, + // it expects to find a saved LR in the bottom word of the frame. + // Unwind the stack back to the pseudo-instruction call site, copy the + // saved LR where the traceback routine will look for it, and make it + // appear that panicdivide was called from that PC. + MOVW 0(R13), LR + ADD $20, R13 + MOVW 8(R13), R1 // actual saved LR + MOVW R1, 0(R13) // expected here for traceback + B runtime·panicdivide(SB) + +// var tab [64]byte +// tab[0] = 255; for i := 1; i <= 63; i++ { tab[i] = (1<<14)/(64+i) } +// laid out here as little-endian uint32s +DATA fast_udiv_tab<>+0x00(SB)/4, $0xf4f8fcff +DATA fast_udiv_tab<>+0x04(SB)/4, $0xe6eaedf0 +DATA fast_udiv_tab<>+0x08(SB)/4, $0xdadde0e3 +DATA fast_udiv_tab<>+0x0c(SB)/4, $0xcfd2d4d7 +DATA fast_udiv_tab<>+0x10(SB)/4, $0xc5c7cacc +DATA fast_udiv_tab<>+0x14(SB)/4, $0xbcbec0c3 +DATA fast_udiv_tab<>+0x18(SB)/4, $0xb4b6b8ba +DATA fast_udiv_tab<>+0x1c(SB)/4, $0xacaeb0b2 +DATA fast_udiv_tab<>+0x20(SB)/4, $0xa5a7a8aa +DATA fast_udiv_tab<>+0x24(SB)/4, $0x9fa0a2a3 +DATA fast_udiv_tab<>+0x28(SB)/4, $0x999a9c9d +DATA fast_udiv_tab<>+0x2c(SB)/4, $0x93949697 +DATA fast_udiv_tab<>+0x30(SB)/4, $0x8e8f9092 +DATA fast_udiv_tab<>+0x34(SB)/4, $0x898a8c8d +DATA fast_udiv_tab<>+0x38(SB)/4, $0x85868788 +DATA fast_udiv_tab<>+0x3c(SB)/4, $0x81828384 +GLOBL fast_udiv_tab<>(SB), RODATA, $64 + +// The linker will pass numerator in R(TMP), and it also +// expects the result in R(TMP) +TMP = 11 + +TEXT _divu(SB), NOSPLIT, $16 + MOVW R(q), 4(R13) + MOVW R(r), 8(R13) + MOVW R(s), 12(R13) + MOVW R(M), 16(R13) + + MOVW R(TMP), R(r) /* numerator */ + MOVW 0(FP), R(q) /* denominator */ + BL udiv<>(SB) + MOVW R(q), R(TMP) + MOVW 4(R13), R(q) + MOVW 8(R13), R(r) + MOVW 12(R13), R(s) + MOVW 16(R13), R(M) + RET + +TEXT _modu(SB), NOSPLIT, $16 + MOVW R(q), 4(R13) + MOVW R(r), 8(R13) + MOVW R(s), 12(R13) + MOVW R(M), 16(R13) + + MOVW R(TMP), R(r) /* numerator */ + MOVW 0(FP), R(q) /* denominator */ + BL udiv<>(SB) + MOVW R(r), R(TMP) + MOVW 4(R13), R(q) + MOVW 8(R13), R(r) + MOVW 12(R13), R(s) + MOVW 16(R13), R(M) + RET + +TEXT _div(SB),NOSPLIT,$16 + MOVW R(q), 4(R13) + MOVW R(r), 8(R13) + MOVW R(s), 12(R13) + MOVW R(M), 16(R13) + MOVW R(TMP), R(r) /* numerator */ + MOVW 0(FP), R(q) /* denominator */ + CMP $0, R(r) + BGE d1 + RSB $0, R(r), R(r) + CMP $0, R(q) + BGE d2 + RSB $0, R(q), R(q) +d0: + BL udiv<>(SB) /* none/both neg */ + MOVW R(q), R(TMP) + B out1 +d1: + CMP $0, R(q) + BGE d0 + RSB $0, R(q), R(q) +d2: + BL udiv<>(SB) /* one neg */ + RSB $0, R(q), R(TMP) +out1: + MOVW 4(R13), R(q) + MOVW 8(R13), R(r) + MOVW 12(R13), R(s) + MOVW 16(R13), R(M) + RET + +TEXT _mod(SB),NOSPLIT,$16 + MOVW R(q), 4(R13) + MOVW R(r), 8(R13) + MOVW R(s), 12(R13) + MOVW R(M), 16(R13) + MOVW R(TMP), R(r) /* numerator */ + MOVW 0(FP), R(q) /* denominator */ + CMP $0, R(q) + RSB.LT $0, R(q), R(q) + CMP $0, R(r) + BGE m1 + RSB $0, R(r), R(r) + BL udiv<>(SB) /* neg numerator */ + RSB $0, R(r), R(TMP) + B out +m1: + BL udiv<>(SB) /* pos numerator */ + MOVW R(r), R(TMP) +out: + MOVW 4(R13), R(q) + MOVW 8(R13), R(r) + MOVW 12(R13), R(s) + MOVW 16(R13), R(M) + RET + +// _mul64by32 and _div64by32 not implemented on arm +TEXT runtime·_mul64by32(SB), NOSPLIT, $0 + MOVW $0, R0 + MOVW (R0), R1 // crash + +TEXT runtime·_div64by32(SB), NOSPLIT, $0 + MOVW $0, R0 + MOVW (R0), R1 // crash |