C51: ?C? Long/Float Math Library Routines

Information in this article applies to:

• C51 Version 6.x and later

NOTE

The Keil C51 library includes a number of helper routines for the C51 compiler. These routines perform mundane tasks that are best not included in-line.

These routines are named using the following convention: ?C?ttfff

where:

• tt is the type field,
• and fff is the operation field.

TYPE FIELD

The type field may be one of the following:

• L indicates 2 longs passed in R0/R1/R2/R3 and R4/R5/R6/R7.
• FP indicates 2 floating-pointer numbers (float) passed in R0/R1/R2/R3 and R4/R5/R6/R7.

OPERATION FIELD

The operation field indicates the math operation to perform:

• ADD indicates addition.
• SUB indicates subtraction.
• MUL indicates multiplication.
• DIV indicates division.
• CMP indicates comparison.
• AND indicates bitwise and.
• OR indicates bitwise or.
• XOR indicates bitwise exclusive or.

The results of the operation are returned in R4/R5/R6/R7.

MORE INFORMATION

• Refer to Floating-point Numbers in the Cx51 User's Guide.

SEE ALSO

• C51: ?C? Library Routines
• C51: ?C? Load and Store Library Routines
• C51: Support for Floating-point Numbers
• C51: Use of F0 and F1 in PSW
• C51: Does the Run-time Library Disable Interrupts?
• C51: Stack Requirements of Run-Time Library Functions

Last Reviewed: Thursday, February 25, 2021