Branching pseudo-instructions

branching.inc

if !def(utilities_branching_inc)
utilities_branching_inc set 1

; ==============================================================================
; branch.inc
;
; Macros for branching pseudo-instructions that are easier to understand at a
; glance.
;
; These macros are intended to be used after a cp, sub, or equivalent operation.
; ==============================================================================

; ===
; JR
; While jr ultimately compiles down to numeric offsets, and these macros will
; thus compile if you pass a number, it's recommended that you only pass labels,
; because these macros don't all expand out to the same length, so let the
; assembler take care of computing the offsets.
; ===

; - macro jrlt label
; Relative jumps to `label` if the previous operation resulted in a
; "less than" condition.
jrlt: macro
  jr c, \1
endm

; - macro jrlte label
; Relative jumps to `label` if the previous operation resulted in a
; "less than or equal to" condition.
jrlte: macro
  jr c, \1
  jr z, \1
endm

; - macro jrgt label
; Relative jumps to `label` if the previous operation resulted in a
; "greater than" condition.
jrgt: macro
  jr c, .endCompare@
  jr nz, \1
.endCompare\@
endm

; - macro jrgte label
; Relative jumps to `label` if the previous operation resulted in a
; "greater than or equal to" condition.
jrgte: macro
  jr nc, \1
endm

; - macro jreq label
; Relative jumps to `label` if the previous operation resulted in an
; "equal to" condition.
jreq: macro
  jr z, \1
endm

; - macro jrne label
; Relative jumps to `label` if the previous operation resulted in a
; "not equal" condition.
jrne: macro
  jr nz, \1
endm

; ===
; JP
; ===

; - macro jplt label
; Jumps to `label` if the previous operation resulted in a "less than"
; condition.
jplt: macro
  jp c, \1
endm

; - macro jplte label
; Jumps to `label` if the previous operation resulted in a "less than or equal
; to" condition.
jplte: macro
  jp c, \1
  jp z, \1
endm

; - macro jpgt label
; Jumps to `label` if the previous operation resulted in a "greater than"
; condition.
jpgt: macro
  jr c, .endCompare@
  jp nz, \1
.endCompare\@
endm

; - macro jpgte label
; Jumps to `label` if the previous operation resulted in a "greater than or
; equal to" condition.
jpgte: macro
  jp nc, \1
endm

; - macro jpeq label
; Jumps to `label` if the previous operation resulted in an "equal to"
; condition.
jpeq: macro
  jp z, \1
endm

; - macro jpne label
; Jumps to `label` if the previous operation resulted in a "not equal"
; condition.
jpne: macro
  jp nz, \1
endm

; ===
; CALL
; ===

; - macro calllt label
; Calls `label` if the previous operation resulted in a "less than" condition.
calllt: macro
  call c, \1
endm

; - macro calllte label
; Calls `label` if the previous operation resulted in a "less than or equal to"
; condition.
calllte: macro
  call c, \1
  call z, \1
endm

; - macro callgt label
; Calls `label` if the previous operation resulted in a "greater than"
; condition.
callgt: macro
  jr c, .endCompare@
  call nz, \1
.endCompare\@
endm

; - macro callgte label
; Calls `label` if the previous operation resulted in a "greater than or equal
; to" condition.
callgte: macro
  call nc, \1
endm

; - macro calleq label
; Calls `label` if the previous operation resulted in an "equal to" condition.
calleq: macro
  call z, \1
endm

; - macro callne label
; Calls `label` if the previous operation resulted in a "not equal" condition.
callne: macro
  call nz, \1
endm

; ===
; RET
; ===

; - macro retlt label
; Returns if the previous operation resulted in a "less than" condition.
retlt: macro
  ret c, \1
endm

; - macro retlte label
; Returns if the previous operation resulted in a "less than or equal to"
; condition.
retlte: macro
  ret c, \1
  ret z, \1
endm

; - macro retgt label
; Returns if the previous operation resulted in a "greater than" condition.
retgt: macro
  jr c, .endCompare@
  ret nz, \1
.endCompare\@
endm

; - macro retgte label
; Returns if the previous operation resulted in a "greater than or equal to"
; condition.
retgte: macro
  ret nc, \1
endm

; - macro reteq label
; Returns if the previous operation resulted in an "equal to" condition.
reteq: macro
  ret z, \1
endm

; - macro retne label
; Returns if the previous operation resulted in a "not equal" condition.
retne: macro
  ret nz, \1
endm

endc

While jr ultimately compiles down to numeric offsets, and these macros will
thus compile if you pass a number, it's recommended that you only pass labels,
because these macros don't all expand out to the same length, so let the
assembler take care of computing the offsets.

This is how I've thought of tackling that problem.

LBL_CHARS EQUS "\"_abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ\""
jrlte: macro
    jr C, \1

    ; If \1 starts like a constant/label, not a number
    IF (STRIN(LBL_CHARS, STRSUB("\1", 1, 1)) != 0)
        jr Z, \1
    ELSE
        jr Z, \1 - 2 ; -2 since jr is two bytes.
    ENDC
endm