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bftst

Test bit field 6802068000 with opt bit

Tests a bit field and sets the condition codes without changing the field.

Select opt p=68020, or use opt bit with the 68000 or 68010, before any code or data

XNZVC –●●00
  • ● set from the result
  • 0 always 0
  • – not changed

Forms

Operands

<ea>
An operand using one of the addressing modes listed for this form. The list determines whether it can be a register, memory or an immediate value. With opt p=68020, an allowed d(An,Xn) or d(PC,Xn) mode also permits the corresponding 68020 indexed and memory indirect forms. See 68020 addressing. More
{offset:width}
A field of 1 to 32 bits, written immediately after the operand. Literal offsets range from 0 to 31, and literal widths from 1 to 32. Either may be a data register, as in {d1:d2}. See the linked section for register values, negative memory offsets and wrapping. More

N copies the field’s highest bit, and Z is set if the field is zero. V and C are cleared, and X is unchanged.

Write the field as {offset:width} immediately after its operand. It selects 1 to 32 bits, counted from bit 31 of a data register or bit 7 of the byte at the memory address. The offset and width may each be a constant or a data register. See bit fields for their ranges, register values and wrapping rules.

opt p=68020
* --- Is any of the low 4 bits set? ---
move.l #%10110000, d0
bftst d0{28:4} ; bits 3 to 0 are all 0: Z is set
seq d1 ; d1 = 255