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Diffstat (limited to 'libc/sysdeps/linux/alpha/divrem.h')
| -rw-r--r-- | libc/sysdeps/linux/alpha/divrem.h | 266 |
1 files changed, 266 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/alpha/divrem.h b/libc/sysdeps/linux/alpha/divrem.h new file mode 100644 index 000000000..d22759e40 --- /dev/null +++ b/libc/sysdeps/linux/alpha/divrem.h @@ -0,0 +1,266 @@ +/* Copyright (C) 1996, 1997 Free Software Foundation, Inc. + Contributed by David Mosberger (davidm@cs.arizona.edu). + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +/* The current Alpha chips don't provide hardware for integer + division. The C compiler expects the functions + + __divqu: 64-bit unsigned long divide + __remqu: 64-bit unsigned long remainder + __divqs/__remqs: signed 64-bit + __divlu/__remlu: unsigned 32-bit + __divls/__remls: signed 32-bit + + These are not normal C functions: instead of the normal calling + sequence, these expect their arguments in registers t10 and t11, and + return the result in t12 (aka pv). Register AT may be clobbered + (assembly temporary), anything else must be saved. */ + +#include <features.h> + +#ifdef __linux__ +# include <asm/gentrap.h> +# include <asm/pal.h> +#else +# include <machine/pal.h> +#endif + +#define mask v0 +#define divisor t0 +#define compare AT +#define tmp1 t2 +#define tmp2 t3 +#define retaddr t9 +#define arg1 t10 +#define arg2 t11 +#define result t12 + +#define v0 $0 /* function return value */ + +#define t0 $1 /* temporary registers (caller-saved) */ +#define t1 $2 +#define t2 $3 +#define t3 $4 +#define t4 $5 +#define t5 $6 +#define t6 $7 +#define t7 $8 + +#define s0 $9 /* saved-registers (callee-saved registers) */ +#define s1 $10 +#define s2 $11 +#define s3 $12 +#define s4 $13 +#define s5 $14 +#define s6 $15 +#define fp s6 /* frame-pointer (s6 in frame-less procedures) */ + +#define a0 $16 /* argument registers (caller-saved) */ +#define a1 $17 +#define a2 $18 +#define a3 $19 +#define a4 $20 +#define a5 $21 + +#define t8 $22 /* more temps (caller-saved) */ +#define t9 $23 +#define t10 $24 +#define t11 $25 +#define ra $26 /* return address register */ +#define t12 $27 + +#define pv t12 /* procedure-variable register */ +#define AT $at /* assembler temporary */ +#define gp $29 /* global pointer */ +#define sp $30 /* stack pointer */ +#define zero $31 /* reads as zero, writes are noops */ + + + +#if IS_REM +# define DIV_ONLY(x,y...) +# define REM_ONLY(x,y...) x,##y +# define modulus result +# define quotient t1 +# define GETSIGN(x) mov arg1, x +# define STACK 32 +#else +# define DIV_ONLY(x,y...) x,##y +# define REM_ONLY(x,y...) +# define modulus t1 +# define quotient result +# define GETSIGN(x) xor arg1, arg2, x +# define STACK 48 +#endif + +#if SIZE == 8 +# define LONGIFY(x,y) mov x,y +# define SLONGIFY(x,y) mov x,y +# define _SLONGIFY(x) +# define NEG(x,y) negq x,y +#else +# define LONGIFY(x,y) zapnot x,15,y +# define SLONGIFY(x,y) sextl x,y +# define _SLONGIFY(x) sextl x,x +# define NEG(x,y) negl x,y +#endif + + .set noreorder + .set noat + + .ent UFUNC_NAME + .globl UFUNC_NAME + + .align 3 +UFUNC_NAME: + lda sp, -STACK(sp) + .frame sp, STACK, retaddr, 0 +#ifdef PROF + stq ra, 0(sp) + stq pv, 8(sp) + stq gp, 16(sp) + + br AT, 1f +1: ldgp gp, 0(AT) + + mov retaddr, ra + lda AT, _mcount + jsr AT, (AT), _mcount + + ldq ra, 0(sp) + ldq pv, 8(sp) + ldq gp, 16(sp) +#endif + .prologue 0 + +$udiv: + stq t0, 0(sp) + LONGIFY (arg2, divisor) + stq t1, 8(sp) + LONGIFY (arg1, modulus) + stq v0, 16(sp) + clr quotient + stq tmp1, 24(sp) + ldiq mask, 1 + DIV_ONLY(stq tmp2,32(sp)) + + beq divisor, $divbyzero + + .align 3 +#if SIZE == 8 + /* Shift divisor left. */ +1: cmpult divisor, modulus, compare + blt divisor, 2f + addq divisor, divisor, divisor + addq mask, mask, mask + bne compare, 1b + unop +2: +#else + /* Shift divisor left using 3-bit shifts as we can't overflow. + This results in looping three times less here, but up to + two more times later. Thus using a large shift isn't worth it. */ +1: cmpult divisor, modulus, compare + s8addq divisor, zero, divisor + s8addq mask, zero, mask + bne compare, 1b +#endif + + /* Now go back to the right. */ +3: DIV_ONLY(addq quotient, mask, tmp2) + srl mask, 1, mask + cmpule divisor, modulus, compare + subq modulus, divisor, tmp1 + DIV_ONLY(cmovne compare, tmp2, quotient) + srl divisor, 1, divisor + cmovne compare, tmp1, modulus + bne mask, 3b + +$done: ldq t0, 0(sp) + ldq t1, 8(sp) + ldq v0, 16(sp) + ldq tmp1, 24(sp) + DIV_ONLY(ldq tmp2, 32(sp)) + lda sp, STACK(sp) + ret zero, (retaddr), 1 + +$divbyzero: + mov a0, tmp1 + ldiq a0, GEN_INTDIV + call_pal PAL_gentrap + mov tmp1, a0 + clr result /* If trap returns, return zero. */ + br $done + + .end UFUNC_NAME + + .ent SFUNC_NAME + .globl SFUNC_NAME + + .align 3 +SFUNC_NAME: + lda sp, -STACK(sp) + .frame sp, STACK, retaddr, 0 +#ifdef PROF + stq ra, 0(sp) + stq pv, 8(sp) + stq gp, 16(sp) + + br AT, 1f +1: ldgp gp, 0(AT) + + mov retaddr, ra + jsr AT, _mcount + + ldq ra, 0(sp) + ldq pv, 8(sp) + ldq gp, 16(sp) +#endif + .prologue 0 + + or arg1, arg2, AT + _SLONGIFY(AT) + bge AT, $udiv /* don't need to mess with signs */ + + /* Save originals and find absolute values. */ + stq arg1, 0(sp) + NEG (arg1, AT) + stq arg2, 8(sp) + cmovge AT, AT, arg1 + stq retaddr, 16(sp) + NEG (arg2, AT) + stq tmp1, 24(sp) + cmovge AT, AT, arg2 + + /* Do the unsigned division. */ + bsr retaddr, UFUNC_NAME + + /* Restore originals and adjust the sign of the result. */ + ldq arg1, 0(sp) + ldq arg2, 8(sp) + GETSIGN (AT) + NEG (result, tmp1) + _SLONGIFY(AT) + ldq retaddr, 16(sp) + cmovlt AT, tmp1, result + ldq tmp1, 24(sp) + + lda sp, STACK(sp) + ret zero, (retaddr), 1 + + .end SFUNC_NAME |