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at 2023-02-26T16:19:45-08:00

Add some comments on what the different jmp conditions mean

I always forget the difference between, say, `:be` and `:le`.  The
former is for unsigned comparisons and the later for signed.

So add some short comments on what the conditions really mean.

@@ -259,21 +259,38 @@
  ;; the first one is the one that is preferred when printing the
  ;; condition code out.
  (defconstant conditions
 -  '((:o . 0)
 +  '(
 +    ;; OF = 1
 +    (:o . 0)
 +    ;; OF = 0
      (:no . 1)
 +    ;; Unsigned <; CF = 1
      (:b . 2) (:nae . 2) (:c . 2)
 +    ;; Unsigned >=; CF = 0
      (:ae . 3) (:nb . 3) (:nc . 3)
 +    ;; Equal; ZF = 1
      (:e . 4) (:eq . 4) (:z . 4)
 +    ;; Not equal; ZF = 0
      (:ne . 5) (:nz . 5)
 +    ;; Unsigned <=; CF = 1 or ZF = 1
      (:be . 6) (:na . 6)
 +    ;; Unsigned >; CF = 1 and ZF = 0
      (:a . 7) (:nbe . 7)
 +    ;; SF = 1
      (:s . 8)
 +    ;; SF = 0
      (:ns . 9)
 +    ;; Parity even
      (:p . 10) (:pe . 10)
 +    ;; Parity odd
      (:np . 11) (:po . 11)
 +    ;; Signed <; SF /= OF
      (:l . 12) (:nge . 12)
 +    ;; Signed >=; SF = OF
      (:ge . 13) (:nl . 13)
 +    ;; Signed <=; ZF = 1 or SF /= OF
      (:le . 14) (:ng . 14)
 +    ;; Signed >; ZF =0 and SF = OF
      (:g . 15) (:nle . 15)))
  (defun conditional-opcode (condition)