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Motorola MC68340 manual Nested Subroutine Calls, Pipeline Synchronization with the NOP Instruction

Models: MC68340

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Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

5.3.4.5Table Example 5: Surface Interpolations. The various forms of table can be used to perform surface (3D) TBLs. However, since the calculation must be split into a series of 2D TBLs, the possibility of losing precision in the intermediate results is possible. The following code sequence, incorporating both TBLS and TBLSN, eliminates this possibility.

L0:

 

 

MOVE.W

Dx, Dl

Copy entry number and fraction number

TBLSN.B

〈ea〉 , Dx

 

TBLSN.B

〈ea〉, Dl

 

TBLS.W

Dx:Dl, Dm

Surface interpolation, with round

ASR.L

#8, Dm

Read just the result

BCC.B

L1

No round necessary

ADDQ.B

#1, Dl

Half round up

L1: . . .

 

 

Before execution of this code sequence, Dx must contain fraction and entry numbers for the two TBL, and Dm must contain the fraction for surface interpolation. The 〈ea〉 fields in the TBLSN instructions point to consecutive columns in a 3D table. The TBLS size parameter must be word if the TBLSN size parameter is byte, and must be long word if TBLSN is word. Increased size is necessary because a larger number of significant digits is needed to accommodate the scaled fractional results of the 2D TBL.

5.3.5 Nested Subroutine Calls

The LINK instruction pushes an address onto the stack, saves the stack address at which the address is stored, and reserves an area of the stack for use. Using this instruction in a series of subroutine calls will generate a linked list of stack frames.

The UNLK instruction removes a stack frame from the end of the list by loading an address into the SP and pulling the value at that address from the stack. When the instruction operand is the address of the link address at the bottom of a stack frame, the effect is to remove the stack frame from both the stack and the linked list.

5.3.6 Pipeline Synchronization with the NOP Instruction

Although the no operation (NOP) instruction performs no visible operation, it does force synchronization of the instruction pipeline, since all previous instructions must complete execution before the NOP begins.

5.4 PROCESSING STATES

This section describes the processing states of the CPU32. It includes a functional description of the bits in the supervisor portion of the SR and an overview of actions taken by the processor in response to exception conditions.

5- 36MC68340 USER’S MANUALMOTOROLA

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Motorola MC68340 manual Nested Subroutine Calls, Pipeline Synchronization with the NOP Instruction, Processing States
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MC68340 specifications

The Motorola MC68340 is a highly integrated microprocessor that was introduced in the early 1990s. It belongs to the 68000 family of microprocessors and is designed to cater to the demands of embedded systems, particularly in telecommunications and networking applications. This chip represents a significant evolution in microprocessor technology by combining a microprocessor core with additional peripherals on a single chip, making it an attractive solution for engineers looking to design compact and efficient systems.

One of the key features of the MC68340 is its 32-bit architecture, which allows for significant processing power and data handling capabilities. This architecture enables the processor to handle larger data sizes and perform more complex calculations compared to its 16-bit predecessors. The MC68340 operates at clock speeds typically ranging from 16 MHz to 25 MHz. Its dual instruction pipeline enhances throughput, allowing for simultaneous instruction fetches and executions, which significantly boosts performance.

A notable characteristic of the MC68340 is the inclusion of integrated peripherals, which help reduce the overall component count in a system. Key integrated components include a memory management unit (MMU), a direct memory access (DMA) controller, and various communication interfaces such as serial ports. The memory management capabilities enhance the processor's ability to manage memory resources efficiently, enabling it to support multitasking environments commonly found in modern computing.

In terms of connectivity, the MC68340 features connections for both synchronous and asynchronous serial communication, making it well-suited for networking tasks. The processor supports a range of bus standards, including address and data buses, which facilitate seamless interaction with peripheral devices.

Another important aspect of the MC68340 is its flexibility. The processor supports multiple operating modes, including multiple CPU configurations and compatibility with the Motorola 68000 family, allowing for easier integration into existing systems.

Moreover, the MC68340 boasts low power consumption compared to many of its contemporaries, making it an excellent choice for battery-operated applications, enhancing its appeal in sectors like telecommunications, industrial control, and automotive systems. Its combination of performance, integration, versatility, and efficiency has secured the MC68340 a reputable position in the annals of embedded systems technology, proving to be a valuable asset for developers and engineers alike.