Motorola MCF5282, MCF5281 Emac Instruction Set Summary, Emac Instruction Execution Times

EMAC Instruction Set Summary

3.5EMAC Instruction Set Summary

Table 3-3summarizes EMAC unit instructions.

Table 3-3. EMAC Instruction Summary

Command	Mnemonic	Description
Multiply Signed	MULS <ea>y,Dx	Multiplies two signed operands yielding a signed result
Multiply Unsigned	MULU <ea>y,Dx	Multiplies two unsigned operands yielding an unsigned result
Multiply Accumulate	MAC Ry,RxSF,ACCx	Multiplies two operands and adds/subtracts the product to/from an
	MSAC Ry,RxSF,ACCx	accumulator
Multiply Accumulate	MAC Ry,Rx,<ea>y,Rw,ACCx	Multiplies two operands and combines the product to an
with Load	MSAC Ry,Rx,<ea>y,Rw,ACCx	accumulator while loading a register with the memory operand
Load Accumulator	MOV.L {Ry,#imm},ACCx	Loads an accumulator with a 32-bit operand
Store Accumulator	MOV.L ACCx,Rx	Writes the contents of an accumulator to a CPU register
Copy Accumulator	MOV.L ACCy,ACCx	Copies a 48-bit accumulator
Load MACSR	MOV.L {Ry,#imm},MACSR	Writes a value to MACSR
Store MACSR	MOV.L MACSR,Rx	Write the contents of MACSR to a CPU register
Store MACSR to CCR	MOV.L MACSR,CCR	Write the contents of MACSR to the CCR
Load MAC Mask Reg	MOV.L {Ry,#imm},MASK	Writes a value to the MASK register
Store MAC Mask Reg	MOV.L MASK,Rx	Writes the contents of the MASK to a CPU register
Load AccExtensions01	MOV.L {Ry,#imm},ACCext01	Loads the accumulator 0,1 extension bytes with a 32-bit operand
Load AccExtensions23	MOV.L {Ry,#imm},ACCext23	Loads the accumulator 2,3 extension bytes with a 32-bit operand
Store AccExtensions01	MOV.L ACCext01,Rx	Writes the contents of accumulator 0,1 extension bytes into a CPU
		register
Store AccExtensions23	MOV.L ACCext23,Rx	Writes the contents of accumulator 2,3 extension bytes into a CPU
		register

3.5.1EMAC Instruction Execution Times

The instruction execution times for the EMAC can be found in Section 2.12, “EMAC Instruction Execution Times.”

The EMAC execution pipeline overlaps the AGEX stage of the OEP; that is, the first stage of the EMAC pipeline is the last stage of the basic OEP. EMAC units are designed for sustained, fully-pipelined operation on accumulator load, copy, and multiply-accumulate instructions. However, instructions that store contents of the multiply-accumulate programming model can generate OEP stalls that expose the EMAC execution pipeline depth, as in the following:

mac.w Ry, Rx, Acc0

mov.l Acc0, Rz

3-12 MCF5282 User’s Manual MOTOROLA