divrem_2.asm
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- dnl Alpha mpn_divrem_2 -- Divide an mpn number by a normalized 2-limb number.
- dnl Copyright 2007, 2008 Free Software Foundation, Inc.
- dnl This file is part of the GNU MP Library.
- dnl The GNU MP Library is free software; you can redistribute it and/or modify
- dnl it under the terms of the GNU Lesser General Public License as published
- dnl by the Free Software Foundation; either version 3 of the License, or (at
- dnl your option) any later version.
- dnl The GNU MP Library is distributed in the hope that it will be useful, but
- dnl WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
- dnl or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
- dnl License for more details.
- dnl You should have received a copy of the GNU Lesser General Public License
- dnl along with the GNU MP Library. If not, see http://www.gnu.org/licenses/.
- include(`../config.m4')
- C norm frac
- C ev4
- C ev5 70 70
- C ev6 29 29
- C TODO
- C * Perhaps inline mpn_invert_limb, that would allow us to not save/restore
- C any registers (thus save ~10 cycles per call).
- C * Use negated d1 and/or d0 to speed carry propagation. Might save a cycle
- C or two.
- C * Check cluster delays (for ev6). We very likely could save some cycles.
- C * Use branch-free code for computing di.
- C * CAVEAT: We rely on r19 not being clobbered by mpn_invert_limb call.
- C INPUT PARAMETERS
- define(`qp', `r16')
- define(`fn', `r17')
- define(`up_param', `r18')
- define(`un_param', `r19')
- define(`dp', `r20')
- ASM_START()
- PROLOGUE(mpn_divrem_2)
- ldgp r29, 0(r27)
- lda r30, -80(r30)
- stq r26, 0(r30)
- stq r9, 8(r30)
- stq r10, 16(r30)
- stq r11, 24(r30)
- stq r12, 32(r30)
- stq r13, 40(r30)
- C stq r14, 48(r30)
- stq r15, 56(r30)
- .prologue 1
- stq r16, 64(r30)
- bis r31, r17, r15
- s8addq r19, r18, r13
- lda r13, -24(r13)
- ldq r12, 8(r20)
- ldq r10, 0(r20)
- ldq r11, 16(r13)
- ldq r9, 8(r13)
- bis r31, r31, r3 C most_significant_q_limb = 0
- cmpult r11, r12, r1
- bne r1, L(L8)
- cmpule r11, r12, r1
- cmpult r9, r10, r2
- and r1, r2, r1
- bne r1, L(L8)
- subq r11, r12, r11
- subq r11, r2, r11
- subq r9, r10, r9
- lda r3, 1(r31) C most_significant_q_limb = 1
- L(L8): stq r3, 72(r30)
- addq r15, r19, r19
- lda r19, -3(r19)
- blt r19, L(L10)
- bis r31, r12, r16
- jsr r26, mpn_invert_limb
- ldgp r29, 0(r26)
- mulq r0, r12, r4 C t0 = LO(di * d1)
- umulh r0, r10, r2 C s1 = HI(di * d0)
- addq r4, r10, r4 C t0 += d0
- cmpule r10, r4, r7 C (t0 < d0)
- addq r4, r2, r4 C t0 += s1
- cmpult r4, r2, r1
- subq r1, r7, r7 C t1 (-1, 0, or 1)
- blt r7, L(L42)
- L(L22):
- lda r0, -1(r0) C di--
- cmpult r4, r12, r1 C cy for: t0 -= d1 (below)
- subq r7, r1, r7 C t1 -= cy
- subq r4, r12, r4 C t0 -= d1
- bge r7, L(L22)
- L(L42):
- ldq r16, 64(r30)
- s8addq r19, r16, r16
- ALIGN(16)
- L(loop):
- mulq r11, r0, r5 C q0 (early)
- umulh r11, r0, r6 C q (early)
- addq r5, r9, r8 C q0 += n1
- addq r6, r11, r6 C q += n2
- cmpult r8, r5, r1 C cy for: q0 += n1
- addq r6, r1, r6 C q += cy
- unop
- mulq r12, r6, r1 C LO(d1 * q)
- umulh r10, r6, r7 C t1 = HI(d0 * q)
- subq r9, r1, r9 C n1 -= LO(d1 * q)
- mulq r10, r6, r4 C t0 = LO(d0 * q)
- unop
- cmple r15, r19, r5 C condition and n0...
- beq r5, L(L31)
- ldq r5, 0(r13)
- lda r13, -8(r13)
- L(L31): subq r9, r12, r9 C n1 -= d1
- cmpult r5, r10, r1 C
- subq r9, r1, r9 C
- subq r5, r10, r5 C n0 -= d0
- subq r9, r7, r9 C n1 -= t0
- cmpult r5, r4, r1 C
- subq r9, r1, r2 C
- subq r5, r4, r5 C n0 -= t1
- cmpult r2, r8, r1 C (n1 < q0)
- addq r6, r1, r6 C q += cond
- lda r1, -1(r1) C -(n1 >= q0)
- and r1, r10, r4 C
- addq r5, r4, r9 C n0 += mask & d0
- and r1, r12, r1 C
- cmpult r9, r5, r11 C cy for: n0 += mask & d0
- addq r2, r1, r1 C n1 += mask & d1
- addq r1, r11, r11 C n1 += cy
- cmpult r11, r12, r1 C
- beq r1, L(fix) C
- L(bck): stq r6, 0(r16)
- lda r16, -8(r16)
- lda r19, -1(r19)
- bge r19, L(loop)
- L(L10): stq r9, 8(r13)
- stq r11, 16(r13)
- ldq r0, 72(r30)
- ldq r26, 0(r30)
- ldq r9, 8(r30)
- ldq r10, 16(r30)
- ldq r11, 24(r30)
- ldq r12, 32(r30)
- ldq r13, 40(r30)
- C ldq r14, 48(r30)
- ldq r15, 56(r30)
- lda r30, 80(r30)
- ret r31, (r26), 1
- L(fix): cmpule r11, r12, r1
- cmpult r9, r10, r2
- and r1, r2, r1
- bne r1, L(bck)
- subq r11, r12, r11
- subq r11, r2, r11
- subq r9, r10, r9
- lda r6, 1(r6)
- br L(bck)
- EPILOGUE()
- ASM_END()