maclhws

Multiply Accumulate Low Halfword Signed

maclhws RT, RA, RB

Signed Multiply Accumulate Low Halfword with Saturation.

Details

Multiplies the low halfword (bits 16–31) of RA by the low halfword of RB as signed integers, adds the 32-bit product to RT, and saturates the result to the signed 32-bit range if overflow occurs. This is part of the Embedded (SPE) category and sets the SAT bit in SPEFSCR if saturation occurs.

Pseudocode Operation

product ← EXTS(RA[16:31]) × EXTS(RB[16:31])
result ← RT + product
if result > 2147483647 then
  RT ← 2147483647
  SPEFSCR[SAT] ← 1
elif result < -2147483648 then
  RT ← -2147483648
  SPEFSCR[SAT] ← 1
else
  RT ← result

Example

maclhws r3, r4, r5

Encoding

Binary Layout
4
0
RT
6
RA
11
RB
16
492
21
0
31
 
Format XO-form
Opcode 0x100003D8
Extension Embedded

Operands

  • RT
    Acc/Dest
  • RA
    Src A
  • RB
    Src B