Fujitsu FR20 Home Theater Server User Manual


 
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User Stack Pointer (USP)
Function of user stack pointer (USP: User Stack Pointer) is described.
The user stack pointer (USP) consists of 32-bit.
Figure 3.3-6 shows the bit configuration of the user stack pointer (USP).
Figure 3.3-6 User stack pointer (USP)
USP is the user stack pointer.
When the S flag is "1", the USP functions as R15. The USP can be specified explicitly. The initial value by
reset is irregular.
The USP cannot be used for the RETI instruction.
Multiplication and Division Result Register (MDH/MDL)
Function of multiplication and division result register (MDH/MDL: Multiply & Divide register) is
described.
The multiplication and division result register (MDH/MDL) consists of 32-bit.
Figure 3.3-7 shows the bit configuration of the multiplication and division result register (MDH/MDL).
Figure 3.3-7 Multiplication and division result storage register (MDH/MDL)
MDH and MDL are the multiplication and division register. Each register is 32-bit long.
The initial value by reset is irregular.
Functions when multiplication is executed
In the case of 32-bit x 32-bit multiplication, the 64-bit long operation results are stored in the
multiplication/division results register in the following format.
MDH: Higher 32-bit
MDL: Lower 32-bit
In the case of 16-bit x 16-bit multiplication, the results are stored in the multiplication/division results
register as follows.
MDH: Indeterminate
MDL: 32-bit
Functions when division is executed
When beginning to calculate, the dividend is stored in MDL.
When division is calculated using the DIV0S/DIV0U, DIV1, DIV2, DIV3, or DIV4S commands, the
results are stored in the MDL and MDH as follows.
MDH: surplus
MDL: commerce
XXXXXXXX
H
31 0 Initial value
bit
31 0
bit
MDH
MDL
Initial value
XXXXXXXX
H
XXXXXXXXH