Freescale Semiconductor SC140 specifications Static Programming Rules, Dynamic Programming Rules

Models: SC140

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LPMARK Rules

7.8.2 Static Programming Rules

This section defines new SC140 LPMARK programming rules for correct LPMARKA and LPMARKB instruction use in a VLES, when enabled by an assembler switch. When enabled, these rules apply in addition to the other programming rules.

7.8.2.1 General Grouping Rules

LPMARK Rule G.G.1

The LPMARKA and LPMARKB instructions are not counted for this rule.

7.8.2.2 Prefix Grouping Rules

LPMARK Rule G.P.3

Multiple LPMARKA instructions cannot be grouped in a VLES. Multiple LPMARKB instructions cannot be grouped in a VLES. This LPMARK rule applies to the whole VLES.

LPMARK Rule G.P.6

The LPMARKA and LPMARKB instructions are not counted for this rule.

LPMARK Rule G.P.7

IFc instructions do not affect the LPMARKA and LPMARKB instructions. The LPMARKA and LPMARKB instructions always execute unconditionally, and can be placed anywhere in the assembly source order.

7.8.3 Dynamic Programming Rules

The LPMARK rules in this section are alternate forms of SC140 programming rules detectable from the prefix encoding. Source code that complies with the assembly notation rules is by definition compliant with LPMARK rules. These LPMARK rules allow the simulator to detect dynamic programming rules that are not detectable by the assembler.

7.8.3.1 LPMARK Notation

The LPMARK rules use the VLES address notation “LPA-2, LPA-1, and LPA” (relative to the VLES having LPMARKA set) and “LPB, LPB+1 and LPB+2” (relative to the VLES having LPMARKB set). The minus “-” notation adjusts the VLES address earlier in the object code order.

7.8.3.1.1 Active Loop

In a nested loop structure, more than one loop can be enabled at the same time. A loop is enabled when its LFn bit in SR is set, where n is the loop index. The enabled loop with the highest index is defined as the “active loop”. This definition is dynamic and follows the SC140 loop state machine. The SC140 loop state machine and simulator determine the “active loop” from the LFn bits in SR when a VLES having an LPMARK bit set is executed.

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SC140 DSP Core Reference Manual

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Freescale Semiconductor SC140 Static Programming Rules, Dynamic Programming Rules, General Grouping Rules, Lpmark Notation