@ *****************************************************************
@
@               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
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@ A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT
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@ *********************************************************************

@ Helper functions for 64-bit integer arithmetic.  ARM version.

#include "sysdeps.h"	

@@@ 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        
@ 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        
@ 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
        bx lr
ENDFUNCTION(__i64_shl)