@ libgcc1 routines for ARM cpu. @ Division routines, written by Richard Earnshaw, (rearnsha@armltd.co.uk) /* Copyright (C) 1995, 1996, 1998 Free Software Foundation, Inc. This file is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. In addition to the permissions in the GNU General Public License, the Free Software Foundation gives you unlimited permission to link the compiled version of this file with other programs, and to distribute those programs without any restriction coming from the use of this file. (The General Public License restrictions do apply in other respects; for example, they cover modification of the file, and distribution when not linked into another program.) This file 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 General Public License for more details. You should have received a copy of the GNU General Public License along with this program; see the file COPYING. If not, write to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ /* As a special exception, if you link this library with other files, some of which are compiled with GCC, to produce an executable, this library does not by itself cause the resulting executable to be covered by the GNU General Public License. This exception does not however invalidate any other reasons why the executable file might be covered by the GNU General Public License. */ /* This code is derived from gcc 2.95.3 */ /* I Molton 29/07/01 */ #include #include #include #include #define RET movs #define RETc(x) mov##x##s #define RETCOND ^ dividend .req r0 divisor .req r1 result .req r2 overdone .req r2 curbit .req r3 ip .req r12 sp .req r13 lr .req r14 pc .req r15 ENTRY(__udivsi3) cmp divisor, #0 beq Ldiv0 mov curbit, #1 mov result, #0 cmp dividend, divisor bcc Lgot_result_udivsi3 1: @ Unless the divisor is very big, shift it up in multiples of @ four bits, since this is the amount of unwinding in the main @ division loop. Continue shifting until the divisor is @ larger than the dividend. cmp divisor, #0x10000000 cmpcc divisor, dividend movcc divisor, divisor, lsl #4 movcc curbit, curbit, lsl #4 bcc 1b 2: @ For very big divisors, we must shift it a bit at a time, or @ we will be in danger of overflowing. cmp divisor, #0x80000000 cmpcc divisor, dividend movcc divisor, divisor, lsl #1 movcc curbit, curbit, lsl #1 bcc 2b 3: @ Test for possible subtractions, and note which bits @ are done in the result. On the final pass, this may subtract @ too much from the dividend, but the result will be ok, since the @ "bit" will have been shifted out at the bottom. cmp dividend, divisor subcs dividend, dividend, divisor orrcs result, result, curbit cmp dividend, divisor, lsr #1 subcs dividend, dividend, divisor, lsr #1 orrcs result, result, curbit, lsr #1 cmp dividend, divisor, lsr #2 subcs dividend, dividend, divisor, lsr #2 orrcs result, result, curbit, lsr #2 cmp dividend, divisor, lsr #3 subcs dividend, dividend, divisor, lsr #3 orrcs result, result, curbit, lsr #3 cmp dividend, #0 @ Early termination? movnes curbit, curbit, lsr #4 @ No, any more bits to do? movne divisor, divisor, lsr #4 bne 3b Lgot_result_udivsi3: mov r0, result RET pc, lr Ldiv0: str lr, [sp, #-4]! bl __div0 mov r0, #0 @ about as wrong as it could be ldmia sp!, {pc}RETCOND /* __umodsi3 ----------------------- */ ENTRY(__umodsi3) cmp divisor, #0 beq Ldiv0 mov curbit, #1 cmp dividend, divisor RETc(cc) pc, lr 1: @ Unless the divisor is very big, shift it up in multiples of @ four bits, since this is the amount of unwinding in the main @ division loop. Continue shifting until the divisor is @ larger than the dividend. cmp divisor, #0x10000000 cmpcc divisor, dividend movcc divisor, divisor, lsl #4 movcc curbit, curbit, lsl #4 bcc 1b 2: @ For very big divisors, we must shift it a bit at a time, or @ we will be in danger of overflowing. cmp divisor, #0x80000000 cmpcc divisor, dividend movcc divisor, divisor, lsl #1 movcc curbit, curbit, lsl #1 bcc 2b 3: @ Test for possible subtractions. On the final pass, this may @ subtract too much from the dividend, so keep track of which @ subtractions are done, we can fix them up afterwards... mov overdone, #0 cmp dividend, divisor subcs dividend, dividend, divisor cmp dividend, divisor, lsr #1 subcs dividend, dividend, divisor, lsr #1 orrcs overdone, overdone, curbit, ror #1 cmp dividend, divisor, lsr #2 subcs dividend, dividend, divisor, lsr #2 orrcs overdone, overdone, curbit, ror #2 cmp dividend, divisor, lsr #3 subcs dividend, dividend, divisor, lsr #3 orrcs overdone, overdone, curbit, ror #3 mov ip, curbit cmp dividend, #0 @ Early termination? movnes curbit, curbit, lsr #4 @ No, any more bits to do? movne divisor, divisor, lsr #4 bne 3b @ Any subtractions that we should not have done will be recorded in @ the top three bits of "overdone". Exactly which were not needed @ are governed by the position of the bit, stored in ip. @ If we terminated early, because dividend became zero, @ then none of the below will match, since the bit in ip will not be @ in the bottom nibble. ands overdone, overdone, #0xe0000000 RETc(eq) pc, lr @ No fixups needed tst overdone, ip, ror #3 addne dividend, dividend, divisor, lsr #3 tst overdone, ip, ror #2 addne dividend, dividend, divisor, lsr #2 tst overdone, ip, ror #1 addne dividend, dividend, divisor, lsr #1 RET pc, lr ENTRY(__divsi3) eor ip, dividend, divisor @ Save the sign of the result. mov curbit, #1 mov result, #0 cmp divisor, #0 rsbmi divisor, divisor, #0 @ Loops below use unsigned. beq Ldiv0 cmp dividend, #0 rsbmi dividend, dividend, #0 cmp dividend, divisor bcc Lgot_result_divsi3 1: @ Unless the divisor is very big, shift it up in multiples of @ four bits, since this is the amount of unwinding in the main @ division loop. Continue shifting until the divisor is @ larger than the dividend. cmp divisor, #0x10000000 cmpcc divisor, dividend movcc divisor, divisor, lsl #4 movcc curbit, curbit, lsl #4 bcc 1b 2: @ For very big divisors, we must shift it a bit at a time, or @ we will be in danger of overflowing. cmp divisor, #0x80000000 cmpcc divisor, dividend movcc divisor, divisor, lsl #1 movcc curbit, curbit, lsl #1 bcc 2b 3: @ Test for possible subtractions, and note which bits @ are done in the result. On the final pass, this may subtract @ too much from the dividend, but the result will be ok, since the @ "bit" will have been shifted out at the bottom. cmp dividend, divisor subcs dividend, dividend, divisor orrcs result, result, curbit cmp dividend, divisor, lsr #1 subcs dividend, dividend, divisor, lsr #1 orrcs result, result, curbit, lsr #1 cmp dividend, divisor, lsr #2 subcs dividend, dividend, divisor, lsr #2 orrcs result, result, curbit, lsr #2 cmp dividend, divisor, lsr #3 subcs dividend, dividend, divisor, lsr #3 orrcs result, result, curbit, lsr #3 cmp dividend, #0 @ Early termination? movnes curbit, curbit, lsr #4 @ No, any more bits to do? movne divisor, divisor, lsr #4 bne 3b Lgot_result_divsi3: mov r0, result cmp ip, #0 rsbmi r0, r0, #0 RET pc, lr ENTRY(__modsi3) mov curbit, #1 cmp divisor, #0 rsbmi divisor, divisor, #0 @ Loops below use unsigned. beq Ldiv0 @ Need to save the sign of the dividend, unfortunately, we need @ ip later on; this is faster than pushing lr and using that. str dividend, [sp, #-4]! cmp dividend, #0 rsbmi dividend, dividend, #0 cmp dividend, divisor bcc Lgot_result_modsi3 1: @ Unless the divisor is very big, shift it up in multiples of @ four bits, since this is the amount of unwinding in the main @ division loop. Continue shifting until the divisor is @ larger than the dividend. cmp divisor, #0x10000000 cmpcc divisor, dividend movcc divisor, divisor, lsl #4 movcc curbit, curbit, lsl #4 bcc 1b 2: @ For very big divisors, we must shift it a bit at a time, or @ we will be in danger of overflowing. cmp divisor, #0x80000000 cmpcc divisor, dividend movcc divisor, divisor, lsl #1 movcc curbit, curbit, lsl #1 bcc 2b 3: @ Test for possible subtractions. On the final pass, this may @ subtract too much from the dividend, so keep track of which @ subtractions are done, we can fix them up afterwards... mov overdone, #0 cmp dividend, divisor subcs dividend, dividend, divisor cmp dividend, divisor, lsr #1 subcs dividend, dividend, divisor, lsr #1 orrcs overdone, overdone, curbit, ror #1 cmp dividend, divisor, lsr #2 subcs dividend, dividend, divisor, lsr #2 orrcs overdone, overdone, curbit, ror #2 cmp dividend, divisor, lsr #3 subcs dividend, dividend, divisor, lsr #3 orrcs overdone, overdone, curbit, ror #3 mov ip, curbit cmp dividend, #0 @ Early termination? movnes curbit, curbit, lsr #4 @ No, any more bits to do? movne divisor, divisor, lsr #4 bne 3b @ Any subtractions that we should not have done will be recorded in @ the top three bits of "overdone". Exactly which were not needed @ are governed by the position of the bit, stored in ip. @ If we terminated early, because dividend became zero, @ then none of the below will match, since the bit in ip will not be @ in the bottom nibble. ands overdone, overdone, #0xe0000000 beq Lgot_result_modsi3 tst overdone, ip, ror #3 addne dividend, dividend, divisor, lsr #3 tst overdone, ip, ror #2 addne dividend, dividend, divisor, lsr #2 tst overdone, ip, ror #1 addne dividend, dividend, divisor, lsr #1 Lgot_result_modsi3: ldr ip, [sp], #4 cmp ip, #0 rsbmi dividend, dividend, #0 RET pc, lr