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Assembly Source File | 1986-05-14 | 23KB | 843 lines

COMMENT ~ FLOATPT.ASM -- Floating Point Conversion Procedures From `BLUEBOOK of ASSEMBLY ROUTINES for the IBM PC & XT' by Christopher L. Morgan Copyright (C) 1984 by The Waite Group, Inc. Purpose: Contents: --------- BIN802DEC -- Convert from 80-bit binary to decimal digits DECDOUBLE -- Double a temporary decimal floating point number DECHALF -- Halve a temporary decimal floating point number DECNORM -- Normalize temporary decimal floating point DFP2SFP -- Convert from double to single precision floating point FIX -- Convert from floating point to 16-bit integer FLOAT -- Convert from 16-bit integer to floating point FPIN -- Convert from external to internal floating point FPINDIGIT -- Input single decimal digit to floating point FPOUT -- Convert from internal to external floating point FPTDIV -- Divide temporary floating point by 10 FPTMUL -- Multiply temporary floating point by 10 FPTNORM -- Normalize temporary floating point SFP2DFP -- Convert from single to double precision floating point SFP2TFP -- Convert from single precision to temporary floating point SGNDEC16IN -- Convert from ASCII signed decimal to binary TDECSHOW -- Display floating point TFP2SFP -- Convert from temporary floating point to single precision _____________________________________________________________________________ ~ CODES SEGMENT EXTRN STDIN:FAR,STDOUT:FAR PUBLIC SGNDEC16IN,TFP2SFP,FPINDIGIT,FPTNORM,FPTMUL,FPTDIV,FPIN PUBLIC SFP2TFP,TDECSHOW,BIN802DEC,DECNORM,DECHALF,DECDOUBLE,FPOUT PUBLIC FIX,FLOAT,SFP2DFP,DFP2SFP,MBINADD,MBINSUB,MBINMUL,MBINDIV ASSUME CS:CODES,DS:DATAS ;Equates SIBYTE EQU BYTE PTR [SI] SIWORD EQU WORD PTR [SI] DIBYTE EQU BYTE PTR [DI] DIWORD EQU WORD PTR [DI] SFPBUFFW0 EQU WORD PTR SFPBUFF+0 SFPBUFFB2 EQU BYTE PTR SFPBUFF+2 SFPBUFFB3 EQU BYTE PTR SFPBUFF+3 SFPBUFFW2 EQU WORD PTR SFPBUFF+2 DFPBUFFW0 EQU WORD PTR DFPBUFF+0 DFPBUFFW2 EQU WORD PTR DFPBUFF+2 DFPBUFFW4 EQU WORD PTR DFPBUFF+4 DFPBUFFW6 EQU WORD PTR DFPBUFF+6 FPTEMP1W0 EQU WORD PTR FPTEMP1+0 FPTEMP1W2 EQU WORD PTR FPTEMP1+2 FPTEMP1W4 EQU WORD PTR FPTEMP1+4 FPTEMP1W6 EQU WORD PTR FPTEMP1+6 FPTEMP1W8 EQU WORD PTR FPTEMP1+8 FPTEMP1B10 EQU BYTE PTR FPTEMP1+10 FPTEMP1W11 EQU WORD PTR FPTEMP1+11 FPTEMP2W0 EQU WORD PTR FPTEMP2+0 FPTEMP2W2 EQU WORD PTR FPTEMP2+2 FPTEMP2W4 EQU WORD PTR FPTEMP2+4 FPTEMP2W6 EQU WORD PTR FPTEMP2+6 FPTEMP2W8 EQU WORD PTR FPTEMP2+8 FPTEMP2B10 EQU BYTE PTR FPTEMP2+10 FPTEMP2W11 EQU WORD PTR FPTEMP2+11 ;__________________________ FLOATING POINT ROUTINES __________________________ ;----------------------------------------------------------------------------- ;Convert from 80-bit binary to decimal digits BIN802DEC PROC NEAR ; ;Clear the string PUSH DI ;Save destination pointer MOV AL,0 ;Zero byte MOV CX,25 ; for a count of 25 BIN802DEC1: MOV [DI],AL ;Zero the byte INC DI ;Point to next byte LOOP BIN802DEC1 ; until done POP DI ;Restore destination pointer ; ;Keep looping BIN802DEC2: PUSH SI ;Save source pointer ; ;Divide mantissa by 10 MOV BX,0 ;Done flag MOV CX,5 ;5 words in number MOV DX,0 ;Previous remainder ADD SI,8 ;Point to high end BIN802DEC3: PUSH CX ;Save count MOV AX,[SI] ;Get 16-bit digit MOV CX,10 ;Divisor of 10 DIV CX ;Divide MOV [SI],AX ;Put 16-bit digit back OR BX,AX ;Check for zero SUB SI,2 ;Point to next 16-bit digit POP CX ;Restore count LOOP BIN802DEC3 MOV [DI],DL ;Remainder is decimal digit INC DI ;Point to next decimal digit POP SI ;Restore source pointer CMP BX,0 ;Was the binary zero ? JNZ BIN802DEC2 ; if so, loop RET ; else return BIN802DEC ENDP ;----------------------------------------------------------------------------- ;Double a temporary decimal floating point number DECDOUBLE PROC NEAR MOV CX,25 ;For a count of 25 MOV AH,0 ;Clear previous carry DECDOUBLE1: MOV AL,[DI] ;Get digit SAL AL,1 ;Multiply by 2 ADD AL,AH ;Add the carry AAM ;Adjust for dec multiplication MOV [DI],AL ;Put the byte back INC DI ;Point to next byte LOOP DECDOUBLE1 RET DECDOUBLE ENDP ;----------------------------------------------------------------------------- ;Halve a temporary decimal floating point number DECHALF PROC NEAR ; ;First shift up one digit MOV CX,25 ;For a count of 25 MOV AL,0 ;Zero previous digit DECHALF1: XCHG AL,[DI] ;Exchange with current digit INC DI ;Point to next digit LOOP DECHALF1 DEC DECEXP ;Decrement decimal digit ; ;Now divide by 2 MOV CX,25 ;For a count of 25 MOV AH,0 ;Clear carry DECHALF2: PUSH CX ;Save count DEC DI ;Point to next digit MOV AL,[DI] ;Get the digit MOV CL,2 ;Divisor of 2 AAD ;Adjust for decimal division DIV CL ;Divide MOV [DI],AL ;Put it back POP CX ;Restore count LOOP DECHALF2 RET DECHALF ENDP ;----------------------------------------------------------------------------- ;Normalize a temporary decimal floating point number DECNORM PROC NEAR ; ;Check top + 1 digit CMP DIBYTE+22,0 ;Is it already zero ? JE DECNORM_XIT ;If so, go ; ;Round up, starting with bottom digit MOV AL,[DI] ;First digit ADD AL,AL ;Double it for rounding MOV AH,0 ;Prepare carry AAA ;Adjust for decimal ; ;Now shift the rest MOV CX,24 ;For a count of 24 DECNORM1: MOV AL,[DI+1] ;Get next digit ADD AL,AH ;Add carry MOV AH,0 ;Prepare next carry AAA ;Adjust for decimal MOV [DI],AL ;Put digit in place INC DI ;Point to next digit LOOP DECNORM1 INC DECEXP ;Increment decimal exponent DECNORM_XIT: RET DECNORM ENDP ;----------------------------------------------------------------------------- ;Convert from double to single precision floating point DFP2SFP PROC FAR PUSH AX ;Save register MOV AX,DFPBUFFW4 ;Get word from double precision MOV SFPBUFFW0,AX ;Put it in single precision MOV AX,DFPBUFFW6 ;Get word from double precision MOV SFPBUFFW2,AX ;Put it in single precision PUSH AX ;Restore register RET DFP2SFP ENDP ;----------------------------------------------------------------------------- ;Convert from internal floating point to internal 16-bit integer (truncate) FIX PROC FAR ; ;The number is in SFPBUFF PUSH CX ;Save registers PUSH AX ; ;Get the mantissa MOV AX,SFPBUFFW0 ;AX gets low part MOV AX,SFPBUFFW2 ;DX gets high part AND DX,007FH ;Just the mantissa OR DX,0080H ;Restore the MSB ; ;Get the exponent MOV CL,SFPBUFFB3 MOV CH,0 ;Extend to 16-bit SUB CX,88H ;Subtract bias + CMP CX,0 ;Check its sign JL FIX1 ; if negative JG FIX3 ; if positive JE FIX4 ; if zero ; ;Shift right FIX1: NEG CX ;Absolute value FIX2: SAR DX,1 ;Shift all bits right RCR AX,1 ;Carry on LOOP FIX2 JMP FIX4 ;End of case negative ; ;Shift left FIX3: SAL AX,1 ;Shift all bits left RCL DX,1 ;Carry on LOOP FIX3 JMP FIX4 ;End of case positive ; ;Check the sign FIX4: MOV AL,SFPBUFFB2 ;Get sign AND AL,80H ;Just bit 7 JZ FIX_XIT ;Is it on ? NEG DX ;Two's complement if negative ; FIX_XIT: POP AX ;Restore registers POP CX RET FIX ENDP ;----------------------------------------------------------------------------- ;Convert from 16-bit integer to floating point FLOAT PROC FAR ; ;The number is in DX PUSH DX ;Save registers PUSH CX PUSH AX MOV AX,0 ;Extend to 32 bits CMP DX,0 ;Check if zero JZ FLOAT4 FLOAT1: MOV CX,9800H ;Initialize exponent & sign ; ;Shift left until normalized FLOAT2: TEST AX,0080H ;Done yet ? JNZ FLOAT3 ;If so, go SAL DX,1 ;If not, shift all bits left RCL AX,1 ;Carry on DEC CH ;Decrement the exponent JMP FLOAT2 ; ;Pack it in FLOAT3: AND AX,007FH ;Just the mantissa OR AX,CX ;Exponent and sign FLOAT4: MOV SFPBUFFW0,DX ;Put lower part into place MOV SFPBUFFW2,AX ;Put upper part into place ; ;Show hex for debugging LEA SI,INTERNAL ;Point to message CALL STDMSG_OUT ;Send it MOV DX,SFPBUFFW2 ;Upper word CALL HEX16OUT ;Show it CALL STD_SPACE ;Skip space POP AX ;Restore registers POP CX POP DX RET FLOAT ENDP ;----------------------------------------------------------------------------- ;Convert from external to internal floating point FPIN PROC FAR PUSH DI ;Save registers PUSH SI PUSH DX PUSH CX PUSH AX ; ;Clear FPTEMP1 buffer LEA DI,FPTEMP1 ;Point to FPTEMP1 MOV AL,0 ;Digit = 0 CALL FPINDIGIT ;Store digit ; ;Clear the decimal flag and the count MOV DECFLAG,0 ;Clear flag MOV DECEXP,0 ;Clear decimal exponent ; ;Look for the sign CALL STD_IN CMP AL,'-' ;Minus ? JZ FPIN1 ;Store it CMP AL,'+' ;Plus ? JZ FPIN2 ;Ignore it JMP FPIN3 ;Anything else gets used ; ;Set sign as negative FPIN1: MOV FPTEMP1B10,80H ;Put sign in place FPIN2: CALL STD_IN ;Get next digit FPIN3: CMP AL,'.' ;Check for a decimal place JNE FPIN4 ;If not, continue ; ;Set decimal flag CMP DECFLAG,0 ;Decimal flag already set? JNE FPIN5 ;Exit if not the first MOV DECFLAG,0FFH ;Set it now JMP FPIN2 ;Go back for a digit FPIN4: SUB AL,30H ;Subtract 30H JL FPIN5 ;Too low ? CMP AL,9 JG FPIN5 ;Too high ? JMP FPIN6 ;Got a digit FPIN5: JMP FPIN15 ;End of mantissa ; ;Load digit as a floating point number FPIN6: LEA DI,FPTEMP2 ;Point to FPTEMP2 CALL FPINDIGIT ;Put in the digit ; ;Multiply result by 10 LEA DI,FPTEMP1 ;Point to FPTEMP1 CALL FPTMUL ;Multiply by 10 ; ;Pick one with larger exponent MOV CX,FPTEMP1W11 ;Get sign of FPTEMP1 SUB CX,FPTEMP2W11 ;Subtract sign of FPTEMP2 JE FPIN11 ;Skip if equal JG FPIN9 ;If exponent FPTEMP2 is less ; ;Exponent of FPTEMP1 is less than exponent of FPTEMP2 FPIN7: NEG CX ;Absolute value of exponent ; ;Shift the bits FPIN8: SAR FPTEMP1W8,1 ;Shift all bits right RCR FPTEMP1W6,1 ;Carry on RCR FPTEMP1W4,1 RCR FPTEMP1W2,1 RCR FPTEMP1W0,1 LOOP FPIN8 ; ;Set the exponent FPIN9: MOV AX,FPTEMP2W11 ;Get exponent of FPTEMP2 MOV FPTEMP1W11,AX ;Put in exponent of FPTEMP1 JMP FPIN11 ;Done with this case ; ;Exponent of FPTEMP2 is less than exponent of FPTEMP1 ; ;Shift the bits FPIN10: SAR FPTEMP2W8,1 ;Shift all bits right RCR FPTEMP2W6,1 ;Carry on RCR FPTEMP2W4,1 RCR FPTEMP2W2,1 RCR FPTEMP2W0,1 LOOP FPIN10 ; ;Set the exponent MOV AX,FPTEMP1W11 ;Get exponent of FPTEMP1 MOV FPTEMP2W11,AX ;Put in exponent of FPTEMP2 JMP FPIN11 ;Done with this case ; ;Add the digit to the result FPIN11: MOV CX,5 ;For a count of 5 words LEA DI,FPTEMP1 ;DI points to FPTEMP1 LEA SI,FPTEMP2 ;SI points to FPTEMP2 CLC FPIN12: MOV AX,[SI] ;Get 16-bit digit from FPTEMP1 INC SI ;Point to next 16-bit digit INC SI ADC [DI],AX ;Add to 16-bit digit of FPTEMP2 INC DI ;Point to next 16-bit digit INC DI LOOP FPIN12 ; ;Normalize LEA DI,FPTEMP1 ;Point to FPTEMP1 CALL FPTNORM ;Renormalize it ; ;Decrement decimal exponent if dec flag is on FPIN13: CMP DECFLAG,0 ;Check decimal flag JE FPIN14 ;Skip if not set DEC DECEXP ;Decrement exponent if set FPIN14: JMP FPIN2 ;Go back for next digit ; ;Adjust for the decimal point FPIN15: ADD AL,30H ;Restore ASCII AND AL,5FH ;Upper or lower case CMP AL,'E' ;Is it 'E' for exponent ? JNE FPIN16 ; ;Get exponent CALL SGNDEC16IN ;Get signed decimal exponent ADD DECEXP,DX ;Add it to current value ; ;Check for sign of decimal exponent FPIN16: MOV CX,DECEXP ;Get decimal exponent CMP CX,0 ;Check its sign JG FPIN17 ;If positive JL FPIN18 ;If negative ; ;Zero count JMP FPIN_XIT ;Done if exponent is zero ; ;Positive decimal exponent FPIN17: PUSH CX ;Save count = decimal exponent ; ;Multiply result by 10 LEA DI,FPTEMP1 ;Point to FPTEMP1 CALL FPTMUL ;Multiply by 10 ; ;Normalize LEA DI,FPTEMP1 ;Point to FPTEMP1 CALL FPTNORM ;Renormalize it POP CX ;Restore the count LOOP FPIN17 JMP FPIN_XIT ;End of this case ; ;Negative count FPIN18: NEG CX ;Absolute value of exponent FPIN19: PUSH CX ;Save the count = exponent ; ;Divide mantissa by 10 LEA DI,FPTEMP1 ;Point to FPTEMP1 CALL FPTDIV ;Divide by 10 ; ;Normalize LEA DI,FPTEMP1 ;Point to FPTEMP1 CALL FPTNORM ;Renormalize it POP CX ;Restore the count LOOP FPIN19 ; FPIN_XIT: CALL TFP2SFP ;Convert to single precision POP AX ;Restore registers POP CX POP DX POP SI POP DI RET FPIN ENDP ;----------------------------------------------------------------------------- ;Convert an input single decimal digit to floating point FPINDIGIT PROC NEAR ; ;Clear the number first PUSH DI ;Save pointer PUSH AX ;Save digit MOV AL,0 ;Zero byte MOV CX,13 ;Do 13 bytes FPINDIGIT1: MOV [DI],AL ;Clear the byte INC DI ;Point to next byte LOOP FPINDIGIT1 ;Loop for more POP AX ;Restore digit POP DI ;Restore pointer ; ;Move the digit into place MOV [DI+9],AL ;Place the digit RET FPINDIGIT ENDP ;----------------------------------------------------------------------------- ;Convert from internal to external floating point FPOUT PROC FAR PUSH DI ;Save registers PUSH SI PUSH DX PUSH BX PUSH CX PUSH AX ; ;Check for zero as a special case MOV AX,SFPBUFFW0 ;Get low word OR AX,SFPBUFFW2 ;Get high word JNZ FPOUT1 ;Go on, if not zero MOV AL,'0' ;Make a zero CALL STD_OUT ;Send it out JMP FPOUT_XIT ;And exit ; ;Convert from single precision to temporary floating point FPOUT1: CALL SFP2TFP ;Convert to temporary format ; ;Initialize exponent for un-normalized position MOV DECEXP,21 ;Exponent = 21 for start ; ;Set the sign MOV AL,FPTEMP1B10 ;Get sign MOV DECSIGN,AL ;Put it away ; ;Convert mantissa to a decimal string LEA SI,FPTEMP1 ;SI points to FPTEMP1 LEA DI,DECBUFF ;DI points to DECBUFF CALL BIN802DEC ;Make decimal string ; ;Check sign of binary exponent MOV CX,FPTEMP1W11 ;Get the binary exponent SUB CX,72 ;Biased by -72 CMP CX,0 ;Check its sign JL FPOUT2 ;If negative JG FPOUT4 ;If positive JMP FPOUT5 ;If zero FPOUT3: PUSH CX ;Absolute value of exponent ; ;Divide by 2 LEA DI,DECBUFF ;Point to DECBUFF CALL DECHALF ;Divide by 2 ; ;Normalize LEA DECBUFF ;Point to DECBUFF CALL DECNORM ;Renormalize POP CX ;Restore count LOOP FPOUT3 JMP FPOUT5 ;End of case ; ;Binary exponent is positive FPOUT4: PUSH CX ;Save count = binary exponent ; ;Multiply by 2 LEA DI,DECBUFF ;Point to DECBUFF CALL DECDOUBLE ;Multiply by 2 ; ;Normalize LEA DECBUFF ;Point to DECBUFF CALL DECNORM ;Renormalize POP CX ;Restore count LOOP FPOUT4 JMP FPOUT5 ;End of case ; ;Output the number FPOUT5: CALL TDECSHOW ;Display the number FPOUT_XIT: POP AX ;Restore registers POP CX POP BX POP DX POP SI POP DI RET FPOUT ENDP ;----------------------------------------------------------------------------- ;Divide a temporary floating point by 10 FPTDIV PROC NEAR ; ;Shift mantissa by 4 places MOV CX,4 ;For a count of 4 FPTDIV1: SAL DIWORD+0,1 ;Shift all digits left RCL DIWORD+2,1 ;Carry on RCL DIWORD+4,1 RCL DIWORD+6,1 RCL DIWORD+8,1 DEC DIWORD+11 LOOP FPTDIV1 ; ;Divide mantissa by 10 MOV CX,5 ;5 words in number MOV DX,0 ;Previous remainder ADD DI,8 ;Point to end FPTDIV2: PUSH CX ;Save count MOV AX,[DI] ;Get 16-bit digit MOV CX,10 ;Divisor of 10 DIV CX ;Divide MOV [DI],AX ;Put 16-bit digit back SUB DI,2 ;Next 16-bit digit POP CX ;Restore count LOOP FPTDIV2 RET FPTDIV ENDP ;----------------------------------------------------------------------------- ;Multiply a temporary floating point by 10 FPTMUL PROC NEAR MOV CX,5 ;For a count of 5 MOV DX,0 ;Carry of zero FPTMUL1: PUSH CX ;Save count MOV AX,DX ;Previous carry XCHG AX,[DI] ;Switch with 16-bit digit MOV DX,10 ;Multiplier of 10 MUL CX ;Multiply ADD [DI],AX ;Add into carry in place ADD DI,2 ;Next 16-bit digit POP CX ;Restore count LOOP FPTMUL1 RET FPTMUL ENDP ;----------------------------------------------------------------------------- ;Normalize a temporary floating point FPTNORM PROC NEAR CMP DIWORD+8,100H ;Test if too high JL FPTNORM_XIT ;Exit if low enough SAR DIWORD+8,1 ;Shift right all bytes RCR DIWORD+6,1 ;Carry on RCR DIWORD+4,1 RCR DIWORD+2,1 RCR DIWORD+0,1 INC DIWORD+11 ;Increment exponent FPTNORM_XIT: RET FPTNORM ENDP ;----------------------------------------------------------------------------- ;Routine to convert from single to double precision floating point SFP2DFP PROC FAR PUSH AX ;Save register ; ;Clear low part of mantissa MOV DFPBUFFW0,0 ;Clear low word MOV DFPBUFFW2,0 ;Clear next low word ; ;Move rest of number MOV AX,SFPBUFFW0 ;Get word from single precision MOV DFPBUFFW4,AX ;Put in double precision MOV AX,SFPBUFFW2 ;Get word from single precision MOV DFPBUFFW6,AX ;Put in double precision POP AX ;Restore registers RET SFP2DFP ENDP ;----------------------------------------------------------------------------- ;Routine to convert from single precision to temporary floating point SFP2TFP PROC NEAR ; ;Clear lower part of mantissa MOV FPTEMP1W0,0 ;Clear word MOV FPTEMP1W2,0 ;Clear word MOV FPTEMP1W4,0 ;Clear word ; ;Move rest of mantissa MOV AX,SFPBUFF20 ;Low 2 bytes MOV FPTEMP1W6,AX ;Put in place MOV AX,SFPBUFFW2 ;High 7 bits AND AX,007FH ;Remove sign OR AX,0080H ;Restore MSB MOV FPTEMP1W8,AX ;Put in place ; ;Move sign MOV AL,SFPBUFFB2 ;In upper byte AND AL,80H ;Just sign bit MOV FPTEMP1B10,AL ;Byte 10 of FPTEMP1 ; ;Move exponent MOV AL,SFPBUFFB3 ;Byte 3 of SFP MOV AH,0 ;Make into a word SUB AX,80H ;Remove bias MOV FPTEMP1W11,AX ;Its 16-bit 2's complement RET SFP2TFP ENDP ;----------------------------------------------------------------------------- ;Routine to convert from ASCII signed decimal to binary SGNDEC16IN PROC FAR MOV DX,0 ;Initialize DX as 0 MOV CH,0 ;Sign flag CALL STD_IN ;Look for sign CMP AL,'-' ;Minus ? JZ SGNDEC16IN1 ;Store it CMP AL,'+' ;Plus ? JZ SGNDEC16IN2 ;Ignore it JMP SGNDEC16IN3 ;Anything else gets used ; ;Set sign as negative SGNDEC16IN1: MOV CH,0FFH ;0FFH is -1 ;Normal loop SGNDEC16IN2: CALL STDIN ;Digit comes in AL ;Already have a digit ? SGNDEC16IN3: SUB AL,30H ;Subtract 30H JL SGNDEC16IN4 ;Check if too low CMP AL,9 JG SGNDEC16IN4 ;Check if too high CBW ;Convert to word PUSH CX ;Save sign PUSH AX ; and digit MOV AX,DX MOV CX,10 ;Multiplier of 10 MUL CX ;Multiply MOV DX,AX ;Result in DX POP AX ;Restore digit ADD DX,AX ;Add in digit POP CX ;Restore count JMP SGNDEC16IN2 ; ;Resolve the sign SGNDEC16IN4: CMP CH,0 ;Is it there ? JE SGNDEC16IN_XIT ;If not, skip NEG DX ;It was negative SGNDEC16IN_XIT: RET SGNDEC16IN ENDP ;----------------------------------------------------------------------------- ;Routine to display floating point TDECSHOW PROC NEAR ; ;Output the sign CMP DECSIGN,0 ;Is it there ? MOV AL,' ' ;Space if not JE TDECSHOW1 ; ;Output a minus sign MOV AL,'-' ;Minus sign TDECSHOW1: CALL STD_OUT ;Send it out ; ;Output the first digit and a decimal point TDECSHOW2: LEA SI,DECBUFF+21 ;Point to first digit MOV AL,[SI] ;Get it DEC SI ;Point to next digit ADD AL,30H ;Make it ASCII CALL STD_OUT ;Send it out ; ;Output the rest of the decimal string MOV CX,7 ;Only 7 more digits TDECSHOW3: MOV AL,[SI] ;Get digit DEC SI ;Point to next digit ADD AL,30H ;Make ASCII CALL STD_OUT ;Send it out LOOP TDECSHOW3 MOV AL,'E' ;E for exponent CALL STD_OUT ;Send it ; ;Now the exponent MOV DX,DECEXP ;Get exponent CMP DX,0 ;Check sign MOV AL,'+' ;Plus sign JGE TDECSHOW_XIT ;If non-negative ; ;If negative exponent NEG DX ;Absolute value of exponent MOV AL,'-' ;Minus sign TDECSHOW_XIT: CALL STD_OUT ;Output sign of exponent CALL DEC16OUT ;Output exponent RET TDECSHOW ENDP ;----------------------------------------------------------------------------- ;Routine to convert from temporary floating point to single precision TFP2SFP PROC NEAR ; ;Move mantissa MOV AX,FPTEMP1W4 ;Below word RCL AX,1 ;Carry for round up MOV AX,FPTEMP1W6 ;Low word ADC AX,0 ;Low word + carry MOV SFPBUFFW0,AX ;Put in place MOV DX,AX ;Check for zero MOV AX,FPTEMP1W8 OR DX,AX ;Check this part, too AND AX,007FH ;Just bottom 7 bits MOV SFPBUFFW2,AX ;Put in place ; ;Move sign bit MOV AL,FPTEMP1B10 ;Byte 10 is sign AND AL,80H OR SFPBUFFB2,AL ;Bit 7 is sign ; ;Move exponent MOV AX,FPTEMP1W11 ;16-bit 2's complement exponent CMP AX,-128 ;Too low ? JL TFP2SFP2 ;Error message CMP AX,127 ;Too high ? JG TFP2SFP3 ;Error message ADD AX,80H ;Bias CMP DX,0 ;Is mantissa 0 ? JNE TFP2SFP1 MOV AL,0 ;Put biased byte back ; ;Normal return ;Show hex for debugging LEA SI,INTERNAL ;Point to message CALL STDMSG_OUT ;Send message MOV DX,SFPBUFFW2 ;Upper word CALL HEX16OUT ;Show it MOV DX,SFPBUFFW0 ;Lower word CALL HEX16OUT ;Show it CALL STD_SPACE ;Skip space CLC ;Clear carry RET ; ;Underflow error TFP2SFP2: LEA SI,UNDERFLOW ;Point to message JMP TFP2SFP4 ; ;Overflow error TFP2SFP3: LEA SI,OVERFLOW ;Point to message JMP TFP2SFP4 TFP2SFP_XIT: CALL STDMSG_OUT ;Send message STC ;Set carry RET TFP2SFP ENDP ;----------------------------------------------------------------------------- ;_____________________________________________________________________________ ; CODES ENDS ; END ;_____________________________________________________________________________ ;>>>>> Physical EOF FLOATPT.ASM <<<<<