Using Numbers

• Double-extended floating-point
• integers more than 1 byte are stored in little endian format
• integers stored in big-endian format within the register
• Signed magnitude

两种方式表示 0
算数运算复杂

补码

• The carry value is ignored in signed integer arithmetic
• movzx source, destination

smaller-sized unsigned => larger-sized unsigned integer(only register)

• movsx
• x/nfu

• f: c, d, x, s
• u: b, h, w, g

• mmx register

64bit. Mapped to the FPU registers

• movq source, destination

MMX, SSE, 64-bit memory location

• print/f
• SIMD

Single Instruction Multiple Data

• MMX

Multimedia Extension

• SSE

Streaming SIMD Extensions
Pentium 4 processor introduce 8 128-bit XMM registers

• quad: 4 * 16 = 64
• dq: double quad: 2 * 4 * 16 = 125
• movdqa/movdqu
• FPU provides a method for supporting signed BCD

8 80-bit, st0..st7, 类似栈
最高位作为符号位, 低 9 字节存储 BCD
Remember that the BCD value is converted to the floating-point representation while in the FPU

• fbld

Packed Decimal (BCD) Load (fbld)

• fbstp

Packed Decimal (BCD) Store and Pop (fbstp)

• Floating-point format

科学计数法

• IEEE Standard 754

• A sign
• A significand
• exponent

• fld source

source can be a 32-, 64-, or 80-bit memory location
flds: single; fldl: double

• fst destnation

fsts: single; fstl: double

• x/f; x/gf
• fld1: +1.0
• fldl2t: log₂¹⁰
• fldl2e: log₂^e
• fldpi: PI
• fldlg2: log₁₀²
• fldln2: log_e²
• fldz: +0.0
  IEEE 754
• 128-bit packed single-precision floating-point (in SSE)
• 128-bit packed double-precision floating-point (in SSE2)
• SSE3 technology, available in Pentium 4 and later processors, adds three additional instructions

moving packed double-precision floating-point