FDIVRP
Usage: FDIVRP dest,src Modifies flags: None
Divides the 'dest' by the 'src' operand and stores the result in the 'dest'. The 'dest' (dividend) is always in an FPU register; the 'src' operand (divisor) can be a register or a memory location. 'Src' operands in memory can be in single-precision or double-precision floating-point format, word or doubleword integer format.
Floating-Point Division
FDIV mem32 ; D8 /6 [8086,FPU]
FDIV mem64 ; DC /6 [8086,FPU]
FDIV fpureg ; D8 F0+r [8086,FPU]
FDIV ST0,fpureg ; D8 F0+r [8086,FPU]
FDIV TO fpureg ; DC F8+r [8086,FPU]
FDIV fpureg,ST0 ; DC F8+r [8086,FPU]
FDIVR mem32 ; D8 /0 [8086,FPU]
FDIVR mem64 ; DC /0 [8086,FPU]
FDIVR fpureg ; D8 F8+r [8086,FPU]
FDIVR ST0,fpureg ; D8 F8+r [8086,FPU]
FDIVR TO fpureg ; DC F0+r [8086,FPU]
FDIVR fpureg,ST0 ; DC F0+r [8086,FPU]
FDIVP fpureg ; DE F8+r [8086,FPU]
FDIVP fpureg,ST0 ; DE F8+r [8086,FPU]
FDIVRP fpureg ; DE F0+r [8086,FPU]
FDIVRP fpureg,ST0 ; DE F0+r [8086,FPU]
FDIV divides ST0 by the given operand and stores the result back in ST0, unless the TO qualifier is given, in which case it divides the given operand by ST0 and stores the result in the operand.
FDIVR does the same thing, but does the division the other way up: so if TO is not given, it divides the given operand by ST0 and stores the result in ST0, whereas if TO is given it divides ST0 by its operand and stores the result in the operand.
FDIVP operates like FDIV TO, but pops the register stack once it has finished.
FDIVRP operates like FDIVR TO, but pops the register stack once it has finished.
The C0, C1, C2, and C3 are undefined.
For FP/Integer divisions, see FIDIV.
FDIVR/FDIVRP/FIDIVR-Reverse Divide
Opcode Instruction Description
D8 /7 FDIVR m32fp Divide m32fp by ST(0) and store result in ST(0)
DC /7 FDIVR m64fp Divide m64fp by ST(0) and store result in ST(0)
D8 F8 +i FDIVR ST(0), ST(i) Divide ST(i) by ST(0) and store result in ST(0)
DC F0 +i FDIVR ST(i), ST(0) Divide ST(0) by ST(i) and store result in ST(i)
DE F0 +i FDIVRP ST(i), ST(0) Divide ST(0) by ST(i), store result in ST(i), and pop the register stack
DE F1 FDIVRP Divide ST(0) by ST(1), store result in ST(1), and pop the register stack
DA /7 FIDIVR m32int Divide m32int by ST(0) and store result in ST(0)
DE /7 FIDIVR m16int Divide m16int by ST(0) and store result in ST(0)
EXAMPLE:
fdivrp st2 st0