Ssat16 And Usat16 - ST STM32F4 Series Programming Manual

The STM32 Cortex-M4 instruction set
3.7.2

SSAT16 and USAT16

Signed Saturate and Unsigned Saturate to any bit position for two halfwords.
Syntax
op{cond} Rd, #n, Rm
Where:
• op' is one of:
SSAT16 Saturates a signed halfword value to a signed range.
USAT16 Saturates a signed halfword value to an unsigned range.
•
'cond' is an optional condition code (see
•
'Rd' is the destination register.
•
'n' specifies the bit position to saturate to:
n ranges from 1 to 16 for SSAT.
n ranges from 0 to 15 for USAT.
•
'Rm' is the register containing the value to saturate.
Operation
The SSAT16 instruction:
1. Saturates two signed 16-bit halfword values of the register with the value to saturate
from selected by the bit position in n.
2. Writes the results as two signed 16-bit halfwords to the destination register.
The USAT16 instruction:
1. Saturates two unsigned 16-bit halfword values of the register with the value to saturate
from selected by the bit position in n.
2. Writes the results as two unsigned halfwords in the destination register.
Restrictions
Do not use SP and do not use PC.
Condition flags
These instructions do not affect the condition code flags.
If saturation occurs, these instructions set the Q flag to 1.
Examples
SSAT16
USAT16NE
126/260
R7, #9, R2 ; Saturates the top and bottom highwords of R2
; as 9-bit values, writes to corresponding halfword
; of R7
R0, #13, R5 ; Conditionally saturates the top and bottom
; halfwords of R5 as 13-bit values, writes to
; corresponding halfword of R0.
DocID022708 Rev 6
Conditional execution on page
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