# *****************************************************************
#
#               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.  PowerPC version.

        .text

### Conversion from double float to unsigned long	

        .balign 16
        .globl __i64_dtou
__i64_dtou:
        stfdu f1, -16(r1)       # extract LO (r4) and HI (r3) halves of double
        lwz r3, 0(r1)
        lwz r4, 4(r1)
        addi r1, r1, 16
        cmpwi r3, 0             # is double < 0?
        blt 1f                  # then it converts to 0
  # extract unbiased exponent  ((HI & 0x7FF00000) >> 20) - (1023 + 52)
        rlwinm r5, r3, 12, 21, 31
        addi r5, r5, -1075
  # check range of exponent
        cmpwi r5, -52           # if EXP < -52, double is < 1.0
        blt 1f
        cmpwi r5, 12            # if EXP >= 64 - 52, double is >= 2^64
        bge 2f
  # extract true mantissa
        rlwinm r3, r3, 0, 12, 31  # HI &= ~0xFFF00000
        oris r3, r3, 0x10         # HI |=  0x00100000
  # shift it appropriately
        cmpwi r5, 0
        blt 3f
  # if EXP >= 0, shift left by EXP.  Note that EXP < 12.
        subfic r6, r5, 32       # r6 = 32 - EXP
        slw r3, r3, r5
        srw r0, r4, r6
        or r3, r3, r0
        slw r4, r4, r5
        blr
  # if EXP < 0, shift right by -EXP.  Note that -EXP <= 52 but can be >= 32.
3:      subfic r5, r5, 0        # r5 = -EXP = shift amount
        subfic r6, r5, 32       # r6 = 32 - amount
        addi r7, r5, -32        # r7 = amount - 32 (see i64_shr.s)
        srw r4, r4, r5
        slw r0, r3, r6
        or r4, r4, r0
        srw r0, r3, r7
        or r4, r4, r0
        srw r3, r3, r5
        blr
  # Special cases
1:      li r3, 0                # result is 0
        li r4, 0
        blr
2:      li r3, -1               # result is MAX_UINT
        li r4, -1
        blr
        .type __i64_dtou, @function
        .size __i64_dtou, .-__i64_dtou