diff options
Diffstat (limited to 'runtime/arm/i64_shl.S')
| -rw-r--r-- | runtime/arm/i64_shl.S | 26 |
1 files changed, 13 insertions, 13 deletions
diff --git a/runtime/arm/i64_shl.S b/runtime/arm/i64_shl.S index 66569d34..2b558cfe 100644 --- a/runtime/arm/i64_shl.S +++ b/runtime/arm/i64_shl.S @@ -17,7 +17,7 @@ @ * 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 @@ -34,38 +34,38 @@ @ Helper functions for 64-bit integer arithmetic. ARM version. -#include "sysdeps.h" +#include "sysdeps.h" -@@@ Shift left +@@@ Shift left @ Note on ARM shifts: the shift amount is taken modulo 256. @ If shift amount mod 256 >= 32, the shift produces 0. @ Algorithm: @ RH = (XH << N) | (XL >> (32-N) | (XL << (N-32)) -@ RL = XL << N +@ RL = XL << N @ If N = 0: @ RH = XH | 0 | 0 @ RL = XL @ If 1 <= N <= 31: 1 <= 32-N <= 31 and 2s5 <= N-32 mod 256 <= 255 @ RH = (XH << N) | (XL >> (32-N) | 0 -@ RL = XL << N +@ RL = XL << N @ If N = 32: @ RH = 0 | XL | 0 @ RL = 0 @ If 33 <= N <= 63: 225 <= 32-N mod 256 <= 255 and 1 <= N-32 <= 31 @ RH = 0 | 0 | (XL << (N-32)) @ RL = 0 - + FUNCTION(__i64_shl) AND r2, r2, #63 @ normalize amount to 0...63 RSB r3, r2, #32 @ r3 = 32 - amount - LSL r1, r1, r2 - LSR r3, r0, r3 - ORR r1, r1, r3 - SUB r3, r2, #32 @ r3 = amount - 32 - LSL r3, r0, r3 - ORR r1, r1, r3 - LSL r0, r0, r2 + LSL Reg0HI, Reg0HI, r2 + LSR r3, Reg0LO, r3 + ORR Reg0HI, Reg0HI, r3 + SUB r3, r2, #32 @ r3 = amount - 32 + LSL r3, Reg0LO, r3 + ORR Reg0HI, Reg0HI, r3 + LSL Reg0LO, Reg0LO, r2 bx lr ENDFUNCTION(__i64_shl) |