Rev. 1.50, 10/04, page 329 of 448
10.1.74 SUBV (Subtract with (V flag) Underflow Check): Arithmetic Instruction
Format
Operation
Instruction Code
Cycle
T Bit
SUBV Rm,Rn
Rn - Rm
→
Rn, underflow
→
T
0011nnnnmmmm1011
1
Underflow
Description:
This instruction subtracts the contents of general register Rm from the contents of
general register Rn, and stores the result in Rn. If underflow occurs, the T bit is set.
Notes:
None
Operation:
SUBV(long m, long n) /* SUBV Rm,Rn */
{
long dest,src,ans;
if ((long)R[n]>=0) dest = 0;
else dest = 1;
if ((long)R[m]>=0) src = 0;
else src = 1;
src += dest;
R[n] -= R[m];
if ((long)R[n]>=0) ans = 0;
else ans = 1;
ans += dest;
if (src==1) {
if (ans==1) T = 1;
else T = 0;
}
else T = 0;
PC += 2;
}
Summary of Contents for SuperH SH-4A
Page 2: ...Rev 1 50 10 04 page ii of xx ...
Page 8: ...Rev 1 50 10 04 page viii of xx ...
Page 116: ...Rev 1 50 10 04 page 96 of 448 ...
Page 178: ...Rev 1 50 10 04 page 158 of 448 ...
Page 206: ...Rev 1 50 10 04 page 186 of 448 ...
Page 231: ...Rev 1 50 10 04 page 211 of 448 Possible Exceptions Slot illegal instruction exception ...
Page 235: ...Rev 1 50 10 04 page 215 of 448 Possible Exceptions Slot illegal instruction exception ...
Page 238: ...Rev 1 50 10 04 page 218 of 448 Possible Exceptions Slot illegal instruction exception ...
Page 408: ...Rev 1 50 10 04 page 388 of 448 Possible Exceptions Inexact Not generated when FPSCR PR 1 ...
Page 446: ...Rev 1 50 10 04 page 426 of 448 ...
Page 468: ...Rev 1 50 10 04 page 448 of 448 ...
Page 471: ......
Page 472: ...SH 4A Software Manual ...