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Diffstat (limited to 'runtime/arm/i64_udivmod.S')
| -rw-r--r-- | runtime/arm/i64_udivmod.S | 79 |
1 files changed, 79 insertions, 0 deletions
diff --git a/runtime/arm/i64_udivmod.S b/runtime/arm/i64_udivmod.S new file mode 100644 index 0000000..e5373ad --- /dev/null +++ b/runtime/arm/i64_udivmod.S @@ -0,0 +1,79 @@ +@ ***************************************************************** +@ +@ The Compcert verified compiler +@ +@ Xavier Leroy, INRIA Paris-Rocquencourt +@ +@ Copyright (c) 2013 Institut National de Recherche en Informatique et +@ en Automatique. +@ +@ Redistribution and use in source and binary forms, with or without +@ modification, are permitted provided that the following conditions are met: +@ * Redistributions of source code must retain the above copyright +@ notice, this list of conditions and the following disclaimer. +@ * Redistributions in binary form must reproduce the above copyright +@ notice, this list of conditions and the following disclaimer in the +@ documentation and/or other materials provided with the distribution. +@ * Neither the name of the <organization> nor the +@ names of its contributors may be used to endorse or promote products +@ derived from this software without specific prior written permission. +@ +@ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +@ "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +@ LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +@ A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT +@ HOLDER> BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, +@ EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, +@ PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR +@ PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF +@ LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING +@ NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS +@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +@ +@ ********************************************************************* + +@ Helper functions for 64-bit integer arithmetic. ARM version. + +#include "sysdeps.h" + +@@@ Auxiliary function for division and modulus. Don't call from C + +@ On entry: N = (r0, r1) numerator D = (r2, r3) divisor +@ On exit: Q = (r4, r5) quotient R = (r0, r1) remainder +@ Locals: M = (r6, r7) mask TMP = r8 temporary + +FUNCTION(__i64_udivmod) + orrs r8, r2, r3 @ is D == 0? + it eq + bxeq lr @ if so, return with unspecified results + MOV r4, #0 @ Q = 0 + MOV r5, #0 + MOV r6, #1 @ M = 1 + MOV r7, #0 +1: cmp r3, #0 @ while ((signed) D >= 0) ... + blt 2f + subs r8, r0, r2 @ ... and N >= D ... + sbcs r8, r1, r3 + blo 2f + adds r2, r2, r2 @ D = D << 1 + adc r3, r3, r3 + adds r6, r6, r6 @ M = M << 1 + adc r7, r7, r7 + b 1b +2: subs r0, r0, r2 @ N = N - D + sbcs r1, r1, r3 + orr r4, r4, r6 @ Q = Q | M + orr r5, r5, r7 + bhs 3f @ if N was >= D, continue + adds r0, r0, r2 @ otherwise, undo what we just did + adc r1, r1, r3 @ N = N + D + bic r4, r4, r6 @ Q = Q & ~M + bic r5, r5, r7 +3: lsrs r7, r7, #1 @ M = M >> 1 + rrx r6, r6 + lsrs r3, r3, #1 @ D = D >> 1 + rrx r2, r2 + orrs r8, r6, r7 @ repeat while (M != 0) ... + bne 2b + bx lr +ENDFUNCTION(__i64_udivmod) |