Subversion Repositories ssbcc

; Copyright 2013, Sinclair R.F., Inc.

;

; 8-bit unsigned vs. unsigned comparison operators

; Compare two unsigned 8-bit values for equality.

; ( u1 u2 - f"u1 = u2" )

.function cmp_8bit_uu_eq

  - .return(0=)

; Compare two unsigned 8-bit values for inequality.

; ( u1 u2 - f"u1 != u2" )

.function cmp_8bit_uu_ne

  - .return(0<>)

; Return true if the unsigned value u1 is less than the unsigned value u2.

; Method:  If the msb of u1 and u2 are the same, then then msb of the difference

;          indicates which one is larger.  Otherwise the msb of u1 indicates

;          which one is larger.

; ( u1 u2 - f"u1 < u2" )

.function cmp_8bit_uu_lt

  over over ^ 0x80 & .jumpc(different)

    - 0x80 & .return(0<>)

  :different

    drop 0x80 & .return(0=)

; Return true if the unsigned value u1 is greater than or equal to the unsigned

; value u2.

; ( u1 u2 - f"u1 >= u2" )

.function cmp_8bit_uu_ge

  .call(cmp_8bit_uu_lt) .return(0=)

; Return true if the unsigned value u1 is less than or equal to the unsigned

; value u2.

; ( u1 u2 - f"u1 <= u2" )

.function cmp_8bit_uu_le

  .call(cmp_8bit_uu_lt,swap) .return(0=)

; Return true if the unsigned value u1 is greater than the unsigned value u2.

; ( u1 u2 - f"u1 > u2" )

.function cmp_8bit_uu_gt

  .call(cmp_8bit_uu_lt,swap) .return

; Return the smaller of two unsigned values.

; ( u1 u2 - min(u1,u2) )

.function min_u8

  ; ( u1 u2 - u1 u2 f"u1 >= u2" )

  over .call(cmp_8bit_uu_lt,over) 0=

  ; ( u1 u2 f"u1 >= u2" - u1 u2 ) r:( - f"u1 >= u2" )

  >r

  ; (u1 u2 - u1 u2-u1 )

  over -

  ; ( u1 u2-u1 - u1 u2-u1 f"u1 >= u2" ) r:( f"u1 >= u2" - )

  r>

  ; if u1<u2:  ( u1 u2-u1 f"u1 >= u2" - u1 0 )

  ; otherwise: ( u1 u2-u1 f"u1 >= u2" - u1 u2-u1 )

  &

  ; ( u1 uX - min(u1,u2) )

  .return(+)