Datasheet

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010: Y (scratch register Y)
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011: NULL (discard data)
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100: PINDIRS
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101: PC
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110: ISR (also sets ISR shift counter to Bit count)
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111: EXEC (Execute OSR shift data as instruction)
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Bit count: how many bits to shift out of the OSR. 1…32 bits, 32 is encoded as 00000.
A 32-bit value is written to Destination: the lower Bit count bits come from the OSR, and the remainder are zeroes. This
value is the least significant Bit count bits of the OSR if SHIFTCTRL_OUT_SHIFTDIR is to the right, otherwise it is the most
significant bits.
PINS and PINDIRS use the OUT pin mapping, as described in Section 3.5.6.
If automatic pull is enabled, the OSR is automatically refilled from the TX FIFO if the pull threshold, SHIFTCTRL_PULL_THRESH,
is reached. The output shift count is simultaneously cleared to 0. In this case, the OUT will stall if the TX FIFO is empty,
but otherwise still executes in one cycle. The specifics are given in Section 3.5.4.
OUT EXEC allows instructions to be included inline in the FIFO datastream. The OUT itself executes on one cycle, and the
instruction from the OSR is executed on the next cycle. There are no restrictions on the types of instructions which can
be executed by this mechanism. Delay cycles on the initial OUT are ignored, but the executee may insert delay cycles as
normal.
OUT PC behaves as an unconditional jump to an address shifted out from the OSR.
3.4.5.3. Assembler Syntax
out <destination>, <bit_count>
where:
<destination> Is one of the destinations specified above.
<bit_count> Is a value (see Section 3.3.2) specifying the number of bits to shift (valid range 1-32)
3.4.6. PUSH
3.4.6.1. Encoding
Bit: 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
PUSH
1 0 0 Delay/side-set 0 IfF Blk 0 0 0 0 0
3.4.6.2. Operation
Push the contents of the ISR into the RX FIFO, as a single 32-bit word. Clear ISR to all-zeroes.
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IfFull: If 1, do nothing unless the total input shift count has reached its threshold, SHIFTCTRL_PUSH_THRESH (the same
as for autopush; see Section 3.5.4).
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Block: If 1, stall execution if RX FIFO is full.
PUSH IFFULL helps to make programs more compact, like autopush. It is useful in cases where the IN would stall at an
inappropriate time if autopush were enabled, e.g. if the state machine is asserting some external control signal at this
RP2040 Datasheet
3.4. Instruction Set 345