FATAN H Hyperbolic Arc Tangent FATAN H
Instruction Format:
15 14 13 ~2 11 10 9 8 7
COPROCESSOR
1 '( 1 I ID 0 O
SOURCE DESTINATION
0 RIM 0 SPECIFIER REGISTER
6 5 4 3 2 1 0
EFFECTIVE ADDRESS
0 MODE REGISTER
O 0 [ 0 1 1 1 0
Instruction Fields:
Coprocessor ID Field -- Specifies which coprocessor in the system is to execute this
instruction. Freescale assemblers default to ID = 1 for the FPCP:
Effective Address Field -- Determines the addressing mode for external operands.
If R/M=0, this field is unused, and should be all zeros.
If R/M=1, this field is encoded with an M68000 addressing mode as shown:
Addressing Mode Mode Register
Dn* 000 reg. number:Dn
An -- --
(An) 010
reg, number:An
(An)+ 011
reg. number:An
- (An) 100
reg. number:An
(dlG,An) 101
reg. number:An
(ds,An,Xn) 110
reg. number:An
(bd,An,Xn) 110
reg. number:An
([bd,An,Xn},od) 110
reg. number:An
([bd,An],Xn,od) 110
reg. number:An
*On/,/if <fret> is Byte, Word, Lon 9 or Single.
Addressing Mode Mode Register
(xxx).W 111 000
(xxx).L 111 001
#<data>
111 100
(d16,PC) 111 010
(ds,PC,Xn) 111 011
Ibd,PC,Xn) 111 011
([bd,PC,XnJ,od) 111 011
([bd,PC},Xn,od)
111 011
R/M Field -- Specifies the source operand address mode.
0 -- The operation is register to register.
1 -, The operation is <ea> to register.
Source Specifier Field -- Specifies the source register or data format.
If R/M = 0, specifies the source floating-point data register, FPm.
If R/M -- 1, specifies the source data format:
000 L Long Word Integer
001 S Single Precision Real
010 X Extended Precision Real
011 P Packed Decimal Real
100 W Word Integer
101 D Double Precision Real
110 B Byte Integer
Destination Register Field -- Specifies the destination floating-point data register, FPn.
If R/M=0 and the source and destination fields are equal, then the input operand
is taken from the specified floating-point data register, and the result is then written
into the same register. If the single register syntax is used, Freescale assemblers
• set the source and destination fields to the same value.
MC68881/MC68882 USER'S MANUAL FREESCALE
4-29
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