Rev. 1.50, 10/04, page 240 of 448
10.1.21 EXTS (Extend as Signed): Arithmetic Instruction
Format Operation Instruction Code Cycle T Bit
EXTS.B Rm,Rn Rm sign-extended from
byte → Rn
0110nnnnmmmm1110 1 —
EXTS.W Rm,Rn Rm sign-extended from
word → Rn
0110nnnnmmmm1111 1 —
Description:
This instruction sign-extends the contents of general register Rm and stores the result in Rn.
For a byte specification, the value of Rm bit 7 is transferred to Rn bits 8 to 31. For a word
specification, the value of Rm bit 15 is transferred to Rn bits 16 to 31.
Notes: None
Operation:
EXTSB(long m, long n) /* EXTS.B Rm,Rn */
{
R[n] = R[m];
if ((R[m] & 0x00000080)==0) R[n] & =0x000000FF;
else R[n] |= 0xFFFFFF00;
PC += 2;
}
EXTSW(long m, long n) /* EXTS.W Rm,Rn */
{
R[n] = R[m];
if ((R[m] & 0x00008000)==0) R[n] & =0x0000FFFF;
else R[n] |= 0xFFFF0000;
PC += 2;
}
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