UM0438 datasheet(30/50 Pages) STMICROELECTRONICS

30 / 50 page

Simplified mnemonics for VLE instructions

UM0438

30/50

Only the most useful simplified mnemonics are found in Section A.5: Simplified mnemonics

that incorporate the BO32 and BO16 operands. Unusual cases can still be coded using a

standard branch conditional syntax.

The crS operand

The crS symbols are shown in Table 17 Note that either the symbol or the operand value

can be used in the syntax used with the simplified mnemonic.

To identify a CR bit, an expression in which a CR field symbol is multiplied by 4 and then

added to a bit-number-within-CR-field symbol can be used, (for example, cr0 * 4 + eq).

crn[1]

4 * cr0 + gt (or gt)

4 * cr1 + gt

4 * cr2 + gt

4 * cr3+ gt

—

greater than or floating-point greater than (gt,

fg).

for integer compare instructions:

ra > simm or rb (signed comparison) or ra >

uimm or rb (unsigned comparison).

for floating-point compare instructions: fra >

frb.

crn[2]

4 * cr0 + eq (or eq)

4 * cr1 + eq

4 * cr2 + eq

4 * cr3+ eq

—

equal or floating-point equal (eq, fe).

for integer compare instructions: ra = simm,

uimm, or rb.

for floating-point compare instructions: fra =

frb.

crn[3]

4 * cr0 + so/un (or

so/un)

4 * cr1 + so/un

4 * cr2 + so/un

4 * cr3 + so/un

—

summary overflow or floating-point unordered

(so, fu).

for integer compare instructions, this is a copy

of xer[so] at instruction completion.

for floating-point compare instructions, one or

both of fra and frb is a nan.

Table 16.

BI32 and BI16 operand settings for CR fields for branch comparisons (continued)

crn

bit

bit expression

CR bits

bi32

bi16

Description

AIM BI

operand

Book E 0–1 2–3

0–1

Table 17.

CR field identification symbols

Symbol

BI32[0–1]

BI16

CR Bits

cr0 (default, can be eliminated from syntax)

Implied

32–35

cr1

—

36–39

cr2

—

40–43

cr3

—

44–47

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