ST10R272L - MULTIPLY-ACCUMULATE UNIT (MAC)
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Note
As for the CPU Core SFRs, any write operation with the regular instruction set to a
single byte of a MAC SFR clears the non-addressed complementary byte within the
specified SFR. Non-implemented SFR bits cannot be modified and will always
supply a read value of’0’.
These registers are mapped in the SFR space and can addressed by the regular instruction
set like any SFR. As mentioned previously, they can also be addressed by the new
instruction CoSTORE. This instruction allows the user to access the MAC registers without
any pipeline side effect. CoSTORE uses a specific 5-bit addressing mode called CoReg.
The following table gives the address of the MAC registers in this CoReg addressing mode.
5.4
MAC instruction set summary
The following table gives an overview of the MAC instruction set. All the mnemonics are
listed with the addressing modes that can be used with each instruction.
For each combination of mnemonic and addressing mode this table indicates if it is
repeatable or not
For full details of the MAC instruction set, refer to the ‘ST10 Family Programming Manual’.
Repeat Count
13-bit unsigned integer value
Indicates the number of time minus one a repeated instruction must be executed.
Registers Description
Address
MSW
MAC-Unit Status Word
00000b
MAH
MAC-Unit Accumulator High
00001b
MAS
“limited” MAH /signed
00010b
MAL
MAC-Unit Accumulator Low
00100b
MCW
MAC-Unit Control Word
00101b
MRW
MAC-Unit Repeat Word
00110b
Table 11 MAC register address in CoReg addressing mode
Bit
Function