UM0438 datasheet(32/50 Pages) STMICROELECTRONICS

32 / 50 page

Simplified mnemonics for VLE instructions

UM0438

32/50

Decrement CTR and branch if it is still nonzero (closure of a loop controlled by a count

loaded into CTR) (note that no CR bits are tested).

e_bdnz target

equivalent to

e_bc 2,0,target

Because this instruction does not test a CR bit, the simplified mnemonic should specify

only a target operand. Specifying a CR (for example, e_bdnz 0,target or e_bdnz

cr0,target) may be considered a programming error. Subsequent examples test

conditions).

Branch if condition in CR0 is equal.

e_bt eq,target

equivalent to

e_bc 1,2,target

Other equivalents include e_bt 2,target or the unlikely e_bt 4 * cr0 +

eq,target

Same as (2), but equal condition is in CR3.

e_bt 4 * cr3 + eq,target

equivalent to

e_bc 1,14,target

e_bt 14,target would also work

Branch if bit 47 of CR is false.

bf 15,target

equivalent to

e_bc 0,15,target

bf 4 * cr3 + so,target would also work

Same as (4), but set the link register. This is a form of conditional call.

bfl 15,target

equivalent to

bcl 4,15,target

Table 20 lists simplified mnemonics and syntax for e_bc and se_bc without LR updating.

Table 21 provides simplified mnemonics and syntax for e_bcl.

Table 20.

Simplified mnemonics for e_bc and se_bc without LR update

Branch semantics

e_bc

Simplified

mnemonic

se_bc

Simplified

mnemonic

Branch if condition true

e_bc 1,BI32,target

e_bt BI32,target

(1)

se_bc 1,BI16,target se_bt BI16,target

Branch if condition false

e_bc 0,BI32,target

e_bf BI32,target1 se_bc 0,BI16,target se_bf BI16,target

Decrement CTR, branch if

CTR

≠ 0

e_bc 2,0,target

e_bdnz target(2)

——

Decrement CTR, branch if

CTR = 0

e_bc 3,0,target

e_bdz target2

——

Instructions for which B032 is either 1 (branch if condition true) or 0 (branch if condition false) do not depend on the CTR

value and can be alternately coded by incorporating the condition specified by the BI32 field, as described in Section A.5.2:

Simplified mnemonics that incorporate CR conditions (eliminates BO32 and BO16 and replaces BI32 with crS)

Simplified mnemonics for branch instructions that do not test CR bits should specify only a target. Otherwise, a

programming error may occur.

Table 21.

Simplified mnemonics for e_bcl with LR update

Branch semantics

e_bcl

Simplified

mnemonic

Branch if condition true(1)

e_bcl 1,BI32,target

e_btl BI32,target

Branch if condition false1

e_bcl 0,BI32,target

e_bfl BI32,target

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