now with fewer midnight-isms

diff --git a/src/div_digits_asm.s b/src/div_digits_asm.s
index b11dd92..1ebf86f 100644 (file)
--- a/src/div_digits_asm.s
+++ b/src/div_digits_asm.s
@@ -2,27 +2,25 @@
 .globl div_digits
 .type div_digits, @function
 
-# div_digits(digits, div, size, res, rem)
-# divides an arbint in digits by uint64 div into res with remainder rem
-# Either res or rem may alias digits
-# digits = rdi, div = rsx, size = rdx, res = rcx, rem = r8
+# div_digits(digits, div, size, res)
+# divides an arbint in digits by uint64 div into res, returns remainder
+# res may alias digits
+# digits = rdi, div = rsx, size = rdx, res = rcx,
 div_digits:
-       movq %rdx, %r9
-       leaq -8(%rdi,%r9,8), %rdi       # We want to point to the end of the buffer (LSB)
-       leaq -8(%rcx,%r9,8), %rcx       # We want to point to the end of the buffer (LSB)
-       leaq -8(%r8,%r9,8), %r8         # We want to point to the end of the buffer (LSB)
+       movq %rdx, %r8
+       leaq -8(%rdi,%r8,8), %rdi       # We want to point to the end of the buffer (LSB)
+       leaq -8(%rcx,%r8,8), %rcx       # We want to point to the end of the buffer (LSB)
        movq $0, %rdx
 loop:
        movq (%rdi), %rax
        divq %rsi                       # rdx:rax/rsi => rax, rdx:rax%rsi => rdx
        movq %rax, (%rcx)
-       movq %rdx, (%r8)
-       dec %r9
+       dec %r8
        leaq -8(%rdi), %rdi
        leaq -8(%rcx), %rcx
-       leaq -8(%r8), %r8
        jnz loop
 end:
+       movq %rdx, %rax                 # return the remainder
        ret