## Is a character an angle bracket?  A particularly easy test.
        .globl isntangle
isntangle:
        mov 4(%esp), %eax
isntangle2:     
        or $2, %eax
        sub $'>, %eax           # also sets ZF on match!
        ret

        ## How about, does a character need to be escaped in general HTML?
        ## Here we have 0x22 '"', 0x3C '<', 0x3E '>', and most 
	## importantly 0x26 '&' to deal with.
        ## Brute-force baseline, five instructions for every case:
	.globl safe_without_escaping
safe_without_escaping:
        mov 4(%esp), %eax
        cmp $'&, %eax
        ja isntangle2           # unsigned!
        je 1f
        sub $'", %eax           # ; "
        ret
1:      xor %eax, %eax          # unnecessary if you're using ZF instead of %eax
        ret
        
        ## Could you do it in three or four instructions?
        ## Maybe a more interesting question is whether you can use
        ## SSE instructions to scan several bytes at once for & or <.