Computer Hardware User's Guide

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