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159
11100B–ATARM–31-Jul-12
SAM4S Series [Preliminary]
11.6.8.1
PKHBT and PKHTB
Pack Halfword
Syntax
op{cond} {Rd}, Rn, Rm {, LSL #imm}
op{cond} {Rd}, Rn, Rm {, ASR #imm}
where:
Operation
The PKHBT
instruction:
1.
Writes the value of the bottom halfword of the first operand to the bottom halfword of
the destination register.
2.
If shifted, the shifted value of the second operand is written to the top halfword of the
destination register.
The
PKHTB
instruction:
1.
Writes the value of the top halfword of the first operand to the top halfword of the desti-
nation register.
2.
If shifted, the shifted value of the second operand is written to the bottom halfword of
the destination register.
Restrictions
Rd
must not be SP and must not be PC.
Condition Flags
This instruction does not change the flags.
Examples
PKHBT
R3, R4, R5 LSL #0
; Writes bottom halfword of R4 to bottom halfword
; of R3, writes top halfword of R5, unshifted, to
; top halfword of R3
PKHTB
R4, R0, R2 ASR #1
; Writes R2 shifted right by 1 bit to bottom
; halfword of R4, and writes top halfword of R0
; to top halfword of R4.
op
is one of:
PKHBT
Pack Halfword, bottom and top with shift.
PKHTB
Pack Halfword, top and bottom with shift.
cond
is an optional condition code, see
Rd
is the destination register.
Rn
is the first operand register.
Rm
is the second operand register holding the value to be optionally shifted.
imm
is the shift length. The type of shift length depends on the instruction:
For
PKHBT
LSL
a left shift with a shift length from 1 to 31, 0 means no shift.
For
PKHTB
ASR
an arithmetic shift right with a shift length from 1 to 32,
a shift of 32-bits is encoded as
0b00000
.
Summary of Contents for SAM4S Series
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Page 1143: ...1143 11100B ATARM 31 Jul 12 SAM4S Series Preliminary Figure 43 4 64 lead LQFP Package Drawing ...
Page 1145: ...1145 11100B ATARM 31 Jul 12 SAM4S Series Preliminary Figure 43 5 64 lead QFN Package Drawing ...