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Section 3 DSP Operation
Rev. 4.00 Sep. 14, 2005 Page 108 of 982
REJ09B0023-0400
Table 3.5
Variation of Fixed-Point Multiply Operation
Mnemonic
Function
Source 1
Source 2
Destination
PMULS Signed
multiplication
Se
Sf
Dg
Table 3.6
Correspondence between Operands and Registers
Register Se
Sf
Dg
A0
Yes
A1 Yes
Yes
Yes
M0
Yes
M1
Yes
X0 Yes
Yes
X1 Yes
—
Y0 Yes
Yes
Y1
Yes
Note: The multiply operations basically generate 32-bit operation results. So when a register
providing the guard-bit parts are specified as a destination operand, the guard-bit parts will
copy bit 31 of the operation result.
The multiply operation of the DSP unit side is not integer but fixed-point arithmetic. So, the upper
words of each multiplier and multiplicand are input into a MAC unit as shown in figure 3.8. In the
SH's standard multiply operations, the lower words of both source operands are input into a MAC
unit. The operation result is also different from the SH's case. The SH's multiply operation result is
aligned to the LSB of the destination, but the fixed-point multiply operation result is aligned to the
MSB, so that the LSB of the fixed-point multiply operation result is always 0.
This fixed-point multiply operation is executed in one cycle Multiply operation is always
unconditional, but does not affect any condition code bits, DC, N, Z, V and GT, in DSR.
Overflow Protection: The S bit in SR is effective for this multiply operation in the DSP unit. See
section 3.1.8, Overflow Protection, for details.
If the S bit is 0, overflow occurs only when
H'8000
*
H'8000
((-1.0)
*
(-1.0))
operation is
executed as signed fixed-point multiply. The result is
H'00 8000 0000
but it does not mean
(
+1.0
). If the S bit is 1, overflow is prevented and the result is
H'00 7FFF FFFF
.
Summary of Contents for HD6417641
Page 2: ...Rev 4 00 Sep 14 2005 Page ii of l...
Page 7: ...Rev 4 00 Sep 14 2005 Page vii of l...
Page 11: ...Rev 4 00 Sep 14 2005 Page xi of l USB Universal serial bus WDT Watch dog timer...
Page 12: ...Rev 4 00 Sep 14 2005 Page xii of l...
Page 28: ...Rev 4 00 Sep 14 2005 Page xxviii of l...
Page 204: ...Section 4 Clock Pulse Generator CPG Rev 4 00 Sep 14 2005 Page 154 of 982 REJ09B0023 0400...
Page 212: ...Section 5 Watchdog Timer WDT Rev 4 00 Sep 14 2005 Page 162 of 982 REJ09B0023 0400...
Page 228: ...Section 6 Power Down Modes Rev 4 00 Sep 14 2005 Page 178 of 982 REJ09B0023 0400...
Page 246: ...Section 8 X Y Memory Rev 4 00 Sep 14 2005 Page 196 of 982 REJ09B0023 0400...
Page 318: ...Section 11 User Break Controller UBC Rev 4 00 Sep 14 2005 Page 268 of 982 REJ09B0023 0400...
Page 454: ...Section 12 Bus State Controller BSC Rev 4 00 Sep 14 2005 Page 404 of 982 REJ09B0023 0400...
Page 504: ...Section 14 U Memory Rev 4 00 Sep 14 2005 Page 454 of 982 REJ09B0023 0400...
Page 566: ...Section 17 Compare Match Timer CMT Rev 4 00 Sep 14 2005 Page 516 of 982 REJ09B0023 0400...
Page 868: ...Section 21 A D Converter Rev 4 00 Sep 14 2005 Page 818 of 982 REJ09B0023 0400...
Page 914: ...Section 23 I O Ports Rev 4 00 Sep 14 2005 Page 864 of 982 REJ09B0023 0400...
Page 956: ...Section 24 List of Registers Rev 4 00 Sep 14 2005 Page 906 of 982 REJ09B0023 0400...
Page 1016: ...Section 25 Electrical Characteristics Rev 4 00 Sep 14 2005 Page 966 of 982 REJ09B0023 0400...
Page 1024: ...Appendix Rev 4 00 Sep 14 2005 Page 974 of 982 REJ09B0023 0400...
Page 1032: ...Rev 4 00 Sep 14 2005 Page 982 of 982 REJ09B0023 0400 X X Y data addressing 52 X Y memory 193...
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