Rev. 1.50, 10/04, page 287 of 448
10.1.44 NEGC (Negate with Carry): Arithmetic Instruction
Format Operation Instruction Code Cycle T Bit
NEGC Rm,Rn 0 – Rm – T → Rn,
borrow → T
0110nnnnmmmm1010 1 Borrow
Description: This instruction subtracts the contents of general register Rm and the T bit from 0
and stores the result in Rn. A borrow resulting from the operation is reflected in the T bit. The
NEGC instruction is used for sign inversion of a value exceeding 32 bits.
Notes: None
Operation:
NEGC(long m, long n) /* NEGC Rm,Rn */
{
unsigned long temp;
temp = 0-R[m];
R[n] = temp-T;
if (0<temp) T = 1;
else T = 0;
if (temp<R[n]) T = 1;
PC += 2;
}
Example:
CLRT ;Sign inversion of R0:R1 (64 bits)
NEGC R1,R1 ;Before execution R1 = H'00000001, T = 0
;After execution R1 = H'FFFFFFFF, T = 1
NEGC R0,R0 ;Before execution R0 = H'00000000, T = 1
;After execution R0 = H'FFFFFFFF, T = 1
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