DSPIC30F4013 Microchip Technology Inc., DSPIC30F4013 Datasheet - Page 18

• Manufacturer Part Number: DSPIC30F4013
• Description: Dspic30f3014/4013 High-performance, 16-bit Digital Signal Controllers
• Manufacturer: Microchip Technology Inc.

dsPIC30F3014/4013
2.3
The dsPIC DSC devices feature a 16/16-bit signed
fractional divide operation, as well as 32/16-bit and 16/
16-bit signed and unsigned integer divide operations, in
the form of single instruction iterative divides. The
following instructions and data sizes are supported:
1.
2.
3.
4.
5.
The 16/16 divides are similar to the 32/16 (same number
of iterations), but the dividend is either zero-extended or
sign-extended during the first iteration.
TABLE 2-1:
DS70138E-page 16
DIVF
DIV.sd
DIV.s
DIV.ud
DIV.u
DIVF – 16/16 signed fractional divide
DIV.sd – 32/16 signed divide
DIV.ud – 32/16 unsigned divide
DIV.s– 16/16 signed divide
DIV.u – 16/16 unsigned divide
Instruction
Divide Support
DIVIDE INSTRUCTIONS
Signed fractional divide: Wm/Wn → W0; Rem → W1
Signed divide: (Wm+1:Wm)/Wn → W0; Rem → W1
Signed divide: Wm/Wn → W0; Rem → W1
Unsigned divide: (Wm+1:Wm)/Wn → W0; Rem → W1
Unsigned divide: Wm/Wn → W0; Rem → W1
The divide instructions must be executed within a
REPEAT loop. Any other form of execution (e.g., a
series of discrete divide instructions) will not function
correctly because the instruction flow depends on
RCOUNT. The divide instruction does not automatically
set up the RCOUNT value and it must, therefore, be
explicitly and correctly specified in the REPEAT instruc-
tion, as shown in Table 2-1 (REPEAT will execute the
target instruction {operand value+1} times). The
REPEAT loop count must be setup for 18 iterations of
the DIV/DIVF instruction. Thus, a complete divide
operation requires 19 cycles.
Function
Note:
The divide flow is interruptible. However,
the user needs to save the context as
appropriate.
© 2007 Microchip Technology Inc.