sbf | CS+ V4.01.00

sbf

Subtracts on condition flag.

[Syntax]

-	sbf imm4, reg1, reg2, reg3

-	sbfcnd reg1, reg2, reg3

The following can be specified for imm4:

-	Absolute expression having a value up to 4 bits (0xD cannot be specified)

[Function]

-	Syntax "sbf imm4, reg1, reg2, reg3"

It compares the current flag condition with the flag condition indicated by the value of the lower 4 bits of the absolute expression (see "Table 5.29 sbfcnd Instruction List") specified by the first operand.

If the values match, subtracts the word data of the register specified by the second operand from the word data of the register specified by the third operand. And 1 is subtracted from the subtraction result and that result is stored in the register specified by the fourth operand.

If the values not match, subtracts the word data of the register specified by the second operand from the word data of the register specified by the third operand. And that result is stored in the register specified by the fourth operand.

-	Syntax "sbfcnd reg1, reg2, reg3"

It compares the current flag condition with the flag condition indicated by the string in the "cnd" part.

If the values match, subtracts the word data of the register specified by the first operand from the word data of the register specified by the second operand. And 1 is subtracted from the subtraction result and that result is stored in the register specified by the third operand.

If the values not match, subtracts the word data of the register specified by the first operand from the word data of the register specified by the second operand. And that result is stored in the register specified by the third operand.

[Description]

-	For the sbf instruction, the assembler generates one sbf machine instruction.

-	For the adcond instruction, the assembler generates the corresponding sbf instruction (see "Table 5.29 sbfcnd Instruction List") and converts it to syntax "sbf imm4, reg1, reg2, reg3".

Table 5.29

sbfcnd Instruction List

Instruction	Flag Condition	Meaning of Flag Condition	Instruction Conversion
sbfgt	( (S xor OV) or Z) = 0	Greater than (signed)	sbf 0xF
sbfge	(S xor OV) = 0	Greater than or equal (signed)	sbf 0xE
sbflt	(S xor OV) = 1	Less than (signed)	sbf 0x6
sbfle	( (S xor OV) or Z) = 1	Less than or equal (signed)	sbf 0x7
sbfh	(CY or Z) = 0	Higher (Greater than)	sbf 0xB
sbfnl	CY = 0	Not lower (Greater than or equal)	sbf 0x9
sbfl	CY = 1	Lower (Less than)	sbf 0x1
sbfnh	(CY or Z) = 1	Not higher (Less than or equal)	sbf 0x3
sbfe	Z = 1	Equal	sbf 0x2
sbfne	Z = 0	Not equal	sbf 0xA
sbfv	OV = 1	Overflow	sbf 0x0
sbfnv	OV = 0	No overflow	sbf 0x8
sbfn	S = 1	Negative	sbf 0x4
sbfp	S = 0	Positive	sbf 0xC
sbfc	CY = 1	Carry	sbf 0x1
sbfnc	CY = 0	No carry	sbf 0x9
sbfz	Z = 1	Zero	sbf 0x2
sbfnz	Z = 0	Not zero	sbf 0xA
sbft	always 1	Always 1	sbf 0x5

[Flag]

CY	1 if a borrow occurs from MSB (Most Significant Bit), 0 if not
OV	1 if overflow occurred, 0 if not
S	1 if the result is negative, 0 if not
Z	1 if the result is 0, 0 if not
SAT	---

[Caution]

-	If an absolute expression having a value exceeding 4 bits is specified as imm4 of the sbf instruction, the following message is output, and assembly continues using the lower 4 bits of the specified value.

W0550011 : illegal operand (range error in immediate).

-	If 0xD is specified as imm4 of the sbf instruction, the following message is output, and assembly is stopped.

E0550261 : illegal condition code.