Freescale Semiconductor StarCore SC140 - Manual (Page 190)

5-10 SC140 DSP Core Reference Manual
Instruction Grouping
5.2.4 Prefix Selection Algorithm
The grouping method (or encoding of prefix words) is not specified by the programmer. The assembler
analyzes each execution set and attempts to group the instructions in a way that minimizes the number of
instruction words. If possible, serial grouping is chosen. However, if extra grouping information is
necessary, a one-word prefix is generated. A two-word prefix is generated only when high register banks
are used in the execution set. The assembler encodes the execution set according to these principles, as
shown in Figure 5-3.
IFT inst [inst] IFF inst [inst] Execution of subgroup1 if T==1
Execution of subgroup2 if T==0
IFT inst [inst] Execution of the whole group if T==1
IFF inst [inst] Execution of the whole group if T==0
IFT inst [inst] IFA inst [inst] Execution of subgroup1 if T==1; always execute subgroup2
IFF inst [inst] IFA inst [inst] Execution of subgroup1 if T==0; always execute subgroup2
Table 5-4. Conditional IFc Syntax
Assembly Syntax Meaning