
 156
SAM4CP [DATASHEET]
43051E–ATPL–08/14
Your assembler might place extra restrictions on the use of IT blocks, such as prohibiting the use of assembler directives
within them.
Condition Flags
This instruction does not change the flags.
Example
ITTE   NE           ; Next 3 instructions are conditional
ANDNE  R0, R0, R1   ; ANDNE does not update condition flags
ADDSNE R2, R2, #1   ; ADDSNE updates condition flags
MOVEQ  R2, R3       ; Conditional move
CMP    R0, #9       ; Convert R0 hex value (0 to 15) into ASCII 
                    ; ('0'-'9', 'A'-'F')
ITE    GT           ; Next 2 instructions are conditional
ADDGT  R1, R0, #55  ; Convert 0xA -> 'A'
ADDLE  R1, R0, #48  ; Convert 0x0 -> '0'
IT     GT           ; IT block with only one conditional instruction
ADDGT  R1, R1, #1   ; Increment R1 conditionally
ITTEE  EQ           ; Next 4 instructions are conditional
MOVEQ  R0, R1       ; Conditional move
ADDEQ  R2, R2, #10  ; Conditional add
ANDNE  R3, R3, #1   ; Conditional AND
BNE.W  dloop        ; Branch instruction can only be used in the last
                    ; instruction of an IT block
 IT     NE          ; Next instruction is conditional
 ADD    R0, R0, R1  ; Syntax error: no condition code used in IT block
12.6.10.4 TBB and TBH
Table Branch Byte and Table Branch Halfword.
Syntax
TBB [
Rn
, 
Rm
]
TBH [
Rn
, 
Rm
, LSL #1]
where:
Rn
is the register containing the address of the table of branch lengths.
If 
Rn
 is PC, then the address of the table is the address of the byte immediately following the TBB or TBH
instruction.
Rm
is the index register. This contains an index into the table. For halfword tables, LSL #1 doubles the value
in 
Rm
 to form the right offset into the table.
Operation
These instructions cause a PC-relative forward branch using a table of single byte offsets for TBB, or halfword offsets for
TBH. 
Rn
 provides a pointer to the table, and 
Rm
 supplies an index into the table. For TBB the branch offset is twice the
unsigned value of the byte returned from the table. and for TBH the branch offset is twice the unsigned value of the half-
word returned from the table. The branch occurs to the address at that offset from the address of the byte immediately
after the TBB or TBH instruction.