return result 192 chapter 3 machine level

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Unformatted text preview: .34. All of them perform a comparison between operands ÇÔ ½ and ÇÔ ¾ , where ÇÔ ½ is the top stack element. Each line of the table documents two different comparison types: an ordered comparison used for comparisons such as and , and an unordered comparison used for equality comparisons. The two comparisons differ only in their treatment of NaN values, since there is no relative ordering between NaN’s and other values. For example, if variable x is a NaN and variable y is some other value, then both expressions x < y and x >= y should yield 0. The various forms of comparison instructions also differ in the location of operand ÇÔ ¾ , analogous to the different forms of floating-point load and floating-point arithmetic instructions. Finally, the various forms differ in the number of elements popped off the stack after the comparison is completed. Instructions in the first group shown in the table do not change the stack at all. Even for the case where one of the arguments is in memory, this value is not on the stack at the end. Operations in the second group pop element ÇÔ ½ off the stack. The final operation pops both ÇÔ ½ and ÇÔ ¾ off the stack. The floating-point status wo...
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This note was uploaded on 09/02/2010 for the course ELECTRICAL 360 taught by Professor Schultz during the Spring '10 term at BYU.

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