FPU INSTRUCTIONS

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FPU INSTRUCTIONS
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Outline

• General FPU Instruction format
• FPU Instruction families
• Examples

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FPU Instructions

• Data movement
• Data conversions
• Constant Instructions
• Arithmetic Instructions
• Comparison Instructions
• Transcendental Instructions
• Miscellaneous Instructions

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General FPU Instruction format

• label Fopcode
• label Fopcode op1
• label Fopcode op1,op2
• label FopcodeP ST(1),ST(0)
• op1 Stack Register ST(07), or memory
• op2 Stack Register ST(07)

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Data movement

• FLD memory
• Loads memory short, long or temp real number to
  TOS, TOP (Top Of stack Pointer is decremented)
• FLD ST(i)
• FLD ST(0) duplicates TOS

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Data movement cont.

• FST memory
• Stores TOS to memory in short or long real format
• FSTP memory
• Stores TOS to memory in short, long or temporary
  real format TOP is incremented and TOS set to
  empty

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Data conversion

• FILD memory
• Loads word, doubleword or quadword integer from
  memory and converts to temporary real to TOS,
  decrements TOP
• FIST memory
• Stores TOS memory and converts to word or
  doubleword

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Data conversion cont

• FISTP memory
• Stores TOS to memory and converts to word,
  doubleword or quadword increments TOP, frees TOS
• IF value in TOS is non integer rounding is
  performed according to bits in CTRL word

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Data conversion cont.

• FBLD memory
• Loads and converts Packed BCD operand from memory
  to TOS
• FBSTP memory
• Stores to memory and converts to Packed BCD, pops
  TOS

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Constant instructions

• FLD1 Push 1.0 to TOS
• FLDL2T Push log210 to TOS
• FLDL2E Push log2e to TOS
• FLDPI Push p to TOS
• FLDLG2 Push log102 to TOS
• FLDLN2 Push loge2 to TOS
• FLDZ Push 0.0 to TOS

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Arithmetic instructions

• FIADD memory adds memory word, doubleword or
  quadword integer to TOS
• FADD memory adds memory short, long or temporary
  real to TOS
• FADD st(i) adds st(i) to TOS
• FADDP add TOS to st(1) and pop TOS
• FADDP st(i),st(0) add TOS to ST(i) and pop TOS

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Arithmetic instructions cont.

• FISUB memory subtracts memory word, doubleword
  or quadword integer from TOS
• FSUB memory subtracts memory short, long or
  temporary real from TOS
• FSUB st(0),st(1) subtracts st(i) from TOS
• FSUBP subtracts TOS from st(1) and pop TOS
• FSUBP st(i),st(0) subtracts TOS from ST(i) and
  pop TOS

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Arithmetic instructions cont.

• FSUBR reverse subtract
• FISUBR memory subtracts TOS from memory word,
  doubleword or quadword integer
• FSUBR memory TOS from subtracts memory short,
  long or temporary real
• FSUBR st(0),st(1) subtracts TOS from st(i)
• FSUBRP subtracts st(1) from TOS and pop TOS
• FSUBRP st(i),st(0) subtracts TOS from ST(i) and
  pop TOS

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Arithmetic instructions cont.

• FMUL MULTIPLY
• FMUL memory real
• FIMUL memory int
• FMUL ST(0), ST(i) Multiply ST(0) by ST(i) and
  store in ST(0)
• FMUL ST(i), ST(0) Multiply ST(i) by ST(0) and
  store in ST(i)
• FMULP ST(i), ST(0) Multiply ST(i) by ST(0),
  store result in ST(i), and pop the register
  stack.
• FMULP Multiply ST(1) by ST(0), store result in
  ST(1), and pop the register stack

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Arithmetic instructions cont.

• FDIV division
• FDIV memory real
• FIDIV memory integer divide TOS by memory,
  result in TOS
• FDIV ST(0), ST(i) Divide ST(0) by ST(i) and
  store result in ST(0)
• FDIV ST(i), ST(0) Divide ST(i) by ST(0) and
  store
• result in ST(i)
• FDIVP ST(i), ST(0) Divide ST(i) by ST(0), store
  result in ST(i), and pop the register stack.
• FDIVP Divide ST(1) by ST(0), store result
• in ST(1), and pop the register stack

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Arithmetic instructions cont.

• FDIVR memory real Divide by ST(0) store in TOS
• FDIVR ST(0),ST(i) Divide ST(i) by ST(0) store
  TOS
• FDIVR ST(i),ST(0) Divide ST(0) by ST(i)
  ST(i).
• FDIVRP ST(i), ST(0) Divide ST(0) by ST(i), store
  ST(i), pop the register stack.
• FDIVRP Divide ST(0) by ST(1), store in ST(1),
  pop the register stack.
• FIDIVR memory int Divide by ST(0) store in
  TOS

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Arithmetic instructions cont.

• FRNDINT
• FABS
• FCHS

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Comparison Instructions

• FCOM ST(i) Compare ST(0) with ST(i)
• FCOM Compare ST(0) with ST(1)
• FCOMP ST(i) Compare ST(0) with ST(i) and pop
  register stack
• FCOMP Compare ST(0) with ST(1) and pop register
  stack
• FCOMPP Compare ST(0) with ST(1) and pop register
  stack twice
• FTEST COMPARE WITH 0.0
• Results in C3,C2,C0 bits of FPU status word

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Transcendental Instructions

• FSQRT
• FPTAN
• FPATAN
• FSIN
• FCOS
• fyl2x and fyl2xp1 instructions compute st(1)
  log2(st(0)) and st(1) log2(st(0)1), st(0)gt0
• f2xm1 2ST(0)-1 -1ltST(0)lt1

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Miscellaneous Instructions

• FINIT
• FWAIT
• FFREE ST(i)
• FLDCW
• FSTCW
• FLDENV
• FSTENV