git.y1.nz

commit a107f3d0bc9536bd982b9a5f12b384298d7fa46a
parent 5c3df55198b4c555f794c39d8baad18608b0d65c
Author: Toxa <untoxa@mail.ru>
Date:   Wed, 22 Nov 2023 11:51:02 +0300

GB: fix 8-bit signed modulus

Diffstat:
M
gbdk-lib/libc/asm/sm83/div.s
16
++++++++--------

1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/gbdk-lib/libc/asm/sm83/div.s b/gbdk-lib/libc/asm/sm83/div.s
@@ -31,6 +31,7 @@
         ;; Originally from GBDK by Pascal Felber.
         .module divmod
         .area   _CODE
+
 .globl  __divsuchar
 .globl  __modsuchar
 .globl  __divuschar
@@ -72,10 +73,9 @@ __divuschar:
         jp      .div16
 
 __moduschar:
-        ld      e, a
         ld      d, #0
 
-        ld      a,c             ; Sign extend
+        ld      c, a             ; Sign extend
         rlca
         sbc     a
         ld      b,a
@@ -217,7 +217,7 @@ signexte:
         ;; Take absolute value of divisor
         bit     7,d
         jr      Z,.chkde        ; Jump if divisor is positive
-        sub     a               ; Substract divisor from 0
+        sub     a               ; Subtract divisor from 0
         sub     e
         ld      e,a
         sbc     a               ; Propagate borrow (A=0xFF if borrow)
@@ -227,7 +227,7 @@ signexte:
 .chkde:
         bit     7,b
         jr      Z,.dodiv        ; Jump if dividend is positive
-        sub     a               ; Substract dividend from 0
+        sub     a               ; Subtract dividend from 0
         sub     c
         ld      c,a
         sbc     a               ; Propagate borrow (A=0xFF if borrow)
@@ -241,7 +241,7 @@ signexte:
         pop     af              ; recover sign of quotient
         and     #0x80
         jr      Z,.dorem        ; Jump if quotient is positive
-        sub     a               ; Substract quotient from 0
+        sub     a               ; Subtract quotient from 0
         sub     c
         ld      c,a
         sbc     a               ; Propagate borrow (A=0xFF if borrow)
@@ -252,7 +252,7 @@ signexte:
         pop     af              ; recover sign of remainder
         and     #0x80
         ret     Z               ; Return if remainder is positive
-        sub     a               ; Substract remainder from 0
+        sub     a               ; Subtract remainder from 0
         sub     e
         ld      e,a
         sbc     a               ; Propagate remainder (A=0xFF if borrow)
@@ -303,14 +303,14 @@ signexte:
         ;; If remainder is >= divisor, next bit of quotient is 1. This
         ;;  bit goes to carry
         push    bc              ; Save current remainder
-        ld      a,c             ; Substract divisor from remainder
+        ld      a,c             ; Subtract divisor from remainder
         sbc     e
         ld      c,a
         ld      a,b
         sbc     d
         ld      b,a
         ccf                     ; Complement borrow so 1 indicates a
-                                ;  successful substraction (this is the
+                                ;  successful subtraction (this is the
                                 ;  next bit of quotient)
         jr      C,.drop         ; Jump if remainder is >= dividend
         pop     bc              ; Otherwise, restore remainder

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