Beginning x64 Assembly Programming: From Novice to AVX Professional

© Jo Van Hoey 2019

J. Van HoeyBeginning x64 Assembly Programminghttps://doi.org/10.1007/978-1-4842-5076-1_27

27. Watch Your MXCSR

Jo Van Hoey¹ 

(1)

Hamme, Belgium

 

Before diving into SSE programming, you need to understand the SSE control and status register for floating-point operations, called mxcsr. It is a 32-bit register, of which only the lower 16 bits are used. Here is the layout:

Bit	Mnemonic	Meaning
0	IE	Invalid operation error
1	DE	Denormal error
2	ZE	Divide-by-zero error
3	OE	Overflow error
4	UE	Underflow error
5	PE	Precision error
6	DAZ	Denormals are zeros
7	IM	Invalid operation mask
8	DM	Denormal operation mask
9	ZM	Divide-by-zero mask
10	OM	Overflow mask
11	UM	Underflow mask
12	PM	Precision mask
13	RC	Rounding control
14	RC	Rounding control
15	FZ	Flush to zero

Bits 0 to 5 indicate when ...