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forth: inline kernel's core and str units

This commit is contained in:
Virgil Dupras 2020-03-18 22:18:07 -04:00
parent 548facac0b
commit ae6334906c
4 changed files with 69 additions and 6 deletions

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@ -1,7 +1,6 @@
.inc "user.h"
jp forthMain
.inc "core.asm"
.equ FORTH_RAMSTART RAMSTART
.inc "forth/main.asm"
.inc "forth/util.asm"

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@ -6,6 +6,43 @@
; give us an idea of Forth's compactness.
; These routines below are copy/paste from apps/lib.
; Ensures that Z is unset (more complicated than it sounds...)
; There are often better inline alternatives, either replacing rets with
; appropriate jmps, or if an 8 bit register is known to not be 0, an inc
; then a dec. If a is nonzero, 'or a' is optimal.
unsetZ:
or a ;if a nonzero, Z reset
ret nz
cp 1 ;if a is zero, Z reset
ret
; copy (HL) into DE, then exchange the two, utilising the optimised HL instructions.
; ld must be done little endian, so least significant byte first.
intoHL:
push de
ld e, (hl)
inc hl
ld d, (hl)
ex de, hl
pop de
ret
intoDE:
ex de, hl
call intoHL
ex de, hl ; de preserved by intoHL, so no push/pop needed
ret
; add the value of A into HL
; affects carry flag according to the 16-bit addition, Z, S and P untouched.
addHL:
push de
ld d, 0
ld e, a
add hl, de
pop de
ret
; make Z the opposite of what it is now
toggleZ:
jp z, unsetZ
@ -57,6 +94,38 @@ strcmp:
; early, set otherwise)
ret
; Compares strings pointed to by HL and DE up to A count of characters. If
; equal, Z is set. If not equal, Z is reset.
strncmp:
push bc
push hl
push de
ld b, a
.loop:
ld a, (de)
cp (hl)
jr nz, .end ; not equal? break early. NZ is carried out
; to the called
cp 0 ; If our chars are null, stop the cmp
jr z, .end ; The positive result will be carried to the
; caller
inc hl
inc de
djnz .loop
; We went through all chars with success, but our current Z flag is
; unset because of the cp 0. Let's do a dummy CP to set the Z flag.
cp a
.end:
pop de
pop hl
pop bc
; Because we don't call anything else than CP that modify the Z flag,
; our Z value will be that of the last cp (reset if we broke the loop
; early, set otherwise)
ret
; Given a string at (HL), move HL until it points to the end of that string.
strskip:
push bc

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@ -15,8 +15,6 @@
jp init
.inc "core.asm"
.inc "str.asm"
.equ STDIO_RAMSTART RAMSTART
.equ STDIO_GETC emulGetC

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@ -6,9 +6,6 @@
jp init
.inc "core.asm"
.inc "str.asm"
.equ STDIO_RAMSTART RAMSTART
.equ STDIO_GETC emulGetC
.equ STDIO_PUTC emulPutC