@ *****************************************************************
@
@               The Compcert verified compiler
@
@           Xavier Leroy, INRIA Paris-Rocquencourt
@
@ Copyright (c) 2013 Institut National de Recherche en Informatique et
@  en Automatique.
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@ *********************************************************************

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

        .text

@@@ Conversion from double float to unsigned 64-bit integer	

	.global __i64_dtou
__i64_dtou:
#ifdef VARIANT_hardfloat	
	fmrrd r0, r1, d0
#endif	
        cmp r1, #0              @ is double < 0 ?
        blt 1f                  @ then it converts to 0
  @ extract unbiased exponent ((HI & 0x7FF00000) >> 20) - (1023 + 52) in r2
  @ note: 1023 + 52 = 1075 = 1024 + 51
  @ note: (HI & 0x7FF00000) >> 20 = (HI << 1) >> 21
        mov r2, r1, lsl #1
        mov r2, r2, lsr #21
        sub r2, r2, #51
        sub r2, r2, #1024
  @ check range of exponent
        cmn r2, #52             @ if EXP < -52, double is < 1.0
        blt 1f
        cmp r2, #12             @ if EXP >= 64 - 52, double is >= 2^64
        bge 2f
  @ extract true mantissa
        bic r1, r1, #0xFF000000
        bic r1, r1, #0x00F00000 @ HI &= ~0xFFF00000
        orr r1, r1, #0x00100000 @ HI |= 0x00100000
  @ shift it appropriately
        cmp r2, #0
        blt 3f
  @ EXP >= 0: shift left by EXP.  Note that EXP < 12        
        rsb r3, r2, #32         @ r3 = 32 - amount
        mov r1, r1, lsl r2
        orr r1, r1, r0, lsr r3
        mov r0, r0, lsl r2
	bx lr
  @ EXP < 0: shift right by -EXP.  Note that -EXP <= 52 but can be >= 32        
3:      rsb r2, r2, #0          @ r2 = -EXP - shift amount
        rsb r3, r2, #32         @ r3 = 32 - amount
        mov r0, r0, lsr r2
        orr r0, r0, r1, lsl r3
	sub r3, r2, #32         @ r3 = amount - 32  (see i64_shr.s)
	orr r0, r0, r1, lsr r3
        mov r1, r1, lsr r2
        bx lr
  @ special cases
1:      mov r0, #0              @ result is 0
        mov r1, #0
        bx lr
2:      mvn r0, #0              @ result is 0xFF....FF (MAX_UINT)
        mvn r1, #0
        bx lr
	.type __i64_dtou, %function
        .size __i64_dtou, . - __i64_dtou