Datasheet

127
SAM4S Series [DATASHEET]
11100F–ATARM–29-Jan-14
Operand2 is a flexible second operand. See “Flexible Second Operand” for details of the
options
Operation
These instructions test the value in a register against Operand2. They update the condition flags based on the result, but
do not write the result to a register.
The TST instruction performs a bitwise AND operation on the value in Rn and the value of Operand2. This is the same as
the ANDS instruction, except that it discards the result.
To test whether a bit of Rn is 0 or 1, use the TST instruction with an Operand2 constant that has that bit set to 1 and all
other bits cleared to 0.
The TEQ instruction performs a bitwise Exclusive OR operation on the value in Rn and the value of Operand2. This is the
same as the EORS instruction, except that it discards the result.
Use the TEQ instruction to test if two values are equal without affecting the V or C flags.
TEQ is also useful for testing the sign of a value. After the comparison, the N flag is the logical Exclusive OR of the sign
bits of the two operands.
Restrictions
Do not use SP and do not use PC.
Condition Flags
These instructions:
 Update the N and Z flags according to the result
 Can update the C flag during the calculation of Operand2, see “Flexible Second Operand”
 Do not affect the V flag.
Examples
TST R0, #0x3F8 ; Perform bitwise AND of R0 value to 0x3F8,
; APSR is updated but result is discarded
TEQEQ R10, R9 ; Conditionally test if value in R10 is equal to
; value in R9, APSR is updated but result is discarded.
12.6.5.16 UADD16 and UADD8
Unsigned Add 16 and Unsigned Add 8
Syntax
op{cond}{Rd,} Rn, Rm
where:
op is any of:
UADD16 Performs two 16-bit unsigned integer additions.
UADD8 Performs four 8-bit unsigned integer additions.
cond is an optional condition code, see “Conditional Execution” .
Rd is the destination register.
Rn is the first register holding the operand.
Rm is the second register holding the operand.
Operation
Use these instructions to add 16- and 8-bit unsigned data:
The UADD16 instruction:
1. Adds each halfword from the first operand to the corresponding halfword of the second operand.
2. Writes the unsigned result in the corresponding halfwords of the destination register.