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# godbolt asm uses gcc on a .s (so no CPP macros)
# but passes options straight to as. So --32 instead of -m32

.globl parse_cxx14_int
        .text
parse_cxx14_int:
        xor %eax,%eax           # initialize high bits of digit reader
        cdq                     # also initialize result accumulator edx to 0
	lea 10(%eax), %ecx      # base 10 default
        lodsb                   # fetch first character
        cmp $'0', %al
        jne .Lentry2
    # leading zero.  Legal 2nd characters are b/B (base 2), x/X (base 16)
    # Or NUL terminator = 0 in base 10
    # or any digit or ' separator (octal).  These have ASCII codes below the alphabetic ranges
    lodsb

mov    $8, %cl              # after '0' have either digit, apostrophe, or terminator,
    cmp    $'B', %al            # or 'b'/'B' or 'x'/'X'  (set a new base)
    jb   .Lentry2               # enter the parse loop with base=8 and an already-loaded character
         # else hex or binary. The bit patterns for those letters are very convenient
    and    $0b0010010, %al      # b/B -> 2,   x/X -> 16
    xchg   %eax, %ecx
    jmp  .Lentry

.Lprocessdigit:
    sub  $'0' & (~32), %al
    jb   .Lentry                 # chars below '0' are treated as a separator, including '
    cmp  $10, %al
    jb  .Lnum
    add  $('0'&~32) - 'A' + 10, %al   # digit value = c-'A' + 10.  we have al = c - '0'&~32.
                                        # c = al + '0'&~32.  val = m+'0'&~32 - 'A' + 10
.Lnum:
        imul %ecx, %edx
        add %eax, %edx          # accum = accum * base + newdigit
.Lentry:
        lodsb                   # fetch next character
.Lentry2:
        and $~32, %al           # uppercase letters (and as side effect,
                                # digits are translated to N+16)
        jnz .Lprocessdigit      # space also counts as a terminator
.Lend:
        ret

.byte . - parse_cxx14_int