Texas Instruments TMS320C3x 사용자 설명서

Floating-Point Conversion (IEEE Std. 754)

5-25

Data Formats and Floating-Point Operation

Example 5–7.TMS320C3x-to-IEEE Conversion (Complete Version) (Continued)

*
TOIEEE1

LDF

R0,R0

;

Determine the sign of the number

LDFZ

*+AR1(4),R0

;

If 0, load appropriate number

BND

NEG

;

Branch to NEG if negative (delayed)

ABSF

R0

;

Take the absolute value

;

of the number

LSH

1,R0

;

Eliminate the sign bit in R0

PUSHF

R0

POP

R0

;

Place number in lower 32 bits of R0

ADDI

*+AR1(2),R0

;

Add exponent bias (127)

LSH

±

1,R0

;

Add the positive sign

CONT

TSTB

*+AR1(5),R0

RETSNZ

;

If e > 0, return

TSTB

*+AR1(7),R0

RETSZ

;

If e = 0 & f = 0, return

PUSH

R0

POPF

R0

LSH

±

1,R0

;

Shift f right by one bit

PUSHF

R0

POP

R0

ADDI

*+AR1(6),R0

;

Add 1 to the MSB of f

RETS

NEG

POP

R0

;

Place number in lower 32 bits of R0

BRD

CONT

ADDI

*+ARI(2),R0

;

Add exponent bias (127)

LSH

±

1,R0

;

Make space for the sign

ADDI

*+AR1(3),R0

;

Add the negative sign

RETS