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Diffstat (limited to 'runtime/arm/i64_stof.S')
| -rw-r--r-- | runtime/arm/i64_stof.S | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/runtime/arm/i64_stof.S b/runtime/arm/i64_stof.S new file mode 100644 index 0000000..165063a --- /dev/null +++ b/runtime/arm/i64_stof.S @@ -0,0 +1,77 @@ +@ ***************************************************************** +@ +@ 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. + + .text + +@@@ Conversion from signed 64-bit integer to single float + + .global __i64_stof +__i64_stof: + # Check whether -2^53 <= X < 2^53 + mov r2, r1, asr #21 + mov r3, r1, asr #31 @ (r2,r3) = X >> 53 + adds r2, r2, #1 + adc r3, r3, #0 @ (r2,r3) = X >> 53 + 1 + cmp r3, #2 + blo 1b + # X is large enough that double rounding can occur. + # Avoid it by nudging X away from the points where double rounding + # occurs (the "round to odd" technique) + mov r2, #0x700 + orr r2, r2, #0xFF # r2 = 0x7FF + and r3, r0, r2 # extract bits 0 to 11 of X + add r3, r3, r2 # r3 = (X & 0x7FF) + 0x7FF + # bit 12 of r3 is 0 if all low 12 bits of X are 0, 1 otherwise + # bits 13-31 of r3 are 0 + orr r0, r0, r3 # correct bit number 12 of X + bic r0, r0, r2 # set to 0 bits 0 to 11 of X + # Convert to double +1: fmsr s0, r0 + fuitod d0, s0 @ convert low half to double (unsigned) + fmsr s2, r1 + fsitod d1, s2 @ convert high half to double (signed) + fldd d2, .LC1 @ d2 = 2^32 + fmacd d0, d1, d2 @ d0 = d0 + d1 * d2 = double value of int64 + # Round to single + fcvtsd s0, d0 + # Return result in r0 + fmrs r0, s0 + bx lr + .type __i64_stof, %function + .size __i64_stof, . - __i64_stof + + .balign 8 +.LC1: .quad 0x41f0000000000000 @ 2^32 in double precision |