18.4: Integer / Floating-Point Conversion Instructions

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If integer values are required during floating-point calculations, the integers must be converted into floating-point values. If single precision and double precision floating-point values are required for a series of calculations, they must be converted to single or double so that the operations are performed on a consistent size/type.

Refer to Chapter 3 for a more detailed explanation of the representation details for floating-point values. It is assumed the reader understands the representation details and recognizes the requirement to ensure consistent formats before performing floating operations.

This basic data conversion operations are performed with the convert instruction. The floating-point conversion instructions are summarized as follows:

Instruction	Explanation
cvtss2sd <RXdest>, <src>	Convert 32-bit floating-point source operand to the 64-bit floating-point destination operand. Note 1, destination operand must be floating- point register. Note 2, source operand cannot be an immediate.
Examples:	cvtss2sd xmm0, dword [fltSVar] cvtss2sd xmm3, eax cvtss2sd xmm3, xmm2
cvtsd2ss <RXdest>, <src>	Convert 64-bit floating-point source operand to the 32-bit floating-point destination operand. Note 1, destination operand must be floating- point register. Note 2, source operand cannot be an immediate.
Examples:	cvtsd2ss xmm0, qword [fltDVar] cvtsd2ss xmm1, rax cvtsd2ss xmm3, xmm2
cvtss2si <reg>, <src>	Convert 32-bit floating-point source operand to the 32-bit integer destination operand. Note 1, destination operand must be register. Note 2, source operand cannot be an immediate.
Examples:	cvtss2si xmm1, xmm0 cvtss2si eax, xmm0 cvtss2si eax, dword [fltSVar]
cvtsd2si <reg>, <src>	Convert 64-bit floating-point source operand to the 32-bit integer destination operand. Note 1, destination operand must be register. Note 2, source operand cannot be an immediate.
Examples:	cvtsd2si xmm1, xmm0 cvtsd2si eax, xmm0 cvtsd2si eax, qword [fltDVar]
cvtsi2ss <RXdest>, <src>	Convert 32-bit integer source operand to the 32-bit floating-point destination operand. Note 1, destination operand must be floating- point register. Note 2, source operand cannot be an immediate.
Examples:	cvtsi2ss xmm0, eax cvtsi2ss xmm0, dword [fltDVar]
cvtsi2sd <RXdest>, <src>	Convert 32-bit integer source operand to the 64-bit floating-point destination operand. Note 1, destination operand must be floating- point register. Note 2, source operand cannot be an immediate.
Examples:	cvtsi2sd xmm0, eax cvtsi2sd xmm0, dword [fltDVar]

A more complete list of the instructions is located in Appendix B.