.machine ppc
        .globl  _remove_comment_asm

INT8_MAX        = 127
INT16_MAX       = 32767
BEGIN_COMMENT   = 12074         ; ('/'<<8)+'*'
END_COMMENT     = 10799         ; ('*'<<8)+'/'

;; char *remove_comment_asm(char *s);
;; 
;; r3: char *s
;; r4: char *retval
;; r5: char *buf
;; r6: int in_comment
;; r7: uint32_t next_match
;; r8: uint32_t cs
;;
;; r9: char c (*s)
;; r10: 8
;; r11: 16
_remove_comment_asm:
        mr      r4, r3            ; retval = s;
        mr      r5, r3            ; buf = s;
        li      r6, 0             ; in_comment = 0;
        li      r7, BEGIN_COMMENT ; next_match = BEGIN_COMMENT;
        li      r8, 0             ; cs = 0;
        li      r10, 8
        li      r11, 16

_scan:
        lbz     r9, 0(r3)       ; (c = *s)
        cmpli   cr7, r9, 0      ; while (*s != 0) {
        beq     cr7, _scan_end

        slw     r8, r8, r10     ; cs <<= 8;
        or      r8, r8, r9      ; cs |= *s;
        addi    r3, r3, 1       ; s++;

        ;; if ((cs & INT16_MAX) == next_match) -> _match
        andi.   r12, r8, INT16_MAX
        cmpl    cr7, r7, r12
        beq     cr7, _match

        ;; else if (!in_comment && cs >= (1<<16)) { ...
        cmpli   cr7, r6, 0      ; !in_comment
        lis     r12, 1          ; (1<<16)
        cmpl    cr6, r8, r12    ; cs >= (1<<16)
        cror    26, 25, 26      ; cr6[eq] = cr6[gt] || cr6[eq]
        crand   2, 30, 26       ; cr0[eq] = cr7[eq] && cr6[eq]
        bne     cr0, _scan

        lis     r12, INT8_MAX   ; INT8_MAX<<16
        and     r12, r8, r12    ; cs & (INT8_MAX<<16)
        srwi    r12, r12, 16    ; c = (cs & (INT8_MAX<<16)) >> 16;
        stb     r12, 0(r5)      ; *buf = c;
        addi    r5, r5, 1       ; buf++;
        b       _scan

_match:
        xori    r6, r6, 1       ; in_comment = !in_comment;
        cmpli   cr7, r6, 1      ; in_comment ? ...
        bne     cr7, _set_begin_comment
        li      r7, END_COMMENT ; next_match = END_COMMENT;
        b       _write_before_comment
        
_set_begin_comment:
        li      r7, BEGIN_COMMENT ; next_match = END_COMMENT;

_write_before_comment:
        mr      r13, r8         ; r13 = cs
        li      r8, 0           ; cs = 0
        cmpli   cr7, r6, 1      ; if (in_comment) ...
        bne     cr7, _scan

        lis     r12, INT8_MAX   ; INT8_MAX<<16
        and     r13, r13, r12   ; c = cs & (INT8_MAX<<16)
        srw     r13, r13, r11   ; c >> 16
        stb     r13, 0(r5)      ; *buf = c;
        addi    r5, r5, 1       ; buf++;
        b       _scan

_scan_end:
        cmpli   cr7, r6, 1      ; if (!in_comment) ...
        beq     cr7, _func_return
        cmpli   cr7, r8, 256    ; if (cs >= 256) ...
        blt     cr7, _write_last_byte

        li      r12, INT8_MAX
        slw     r12, r12, r10   ; INT8_MAX<<8
        and     r13, r8, r12    ; c = cs & (INT8_MAX<<8)
        srw     r13, r13, r10   ; c >> 8
        stb     r13, 0(r5)      ; *buf = c;
        addi    r5, r5, 1       ; buf++;

_write_last_byte:
        andi.   r9, r8, INT8_MAX ; cs & INT8_MAX
        stb     r9, 0(r5)        ; *buf = c;
        addi    r5, r5, 1        ; buf++;

_func_return:
        li      r0, 0
        stb     r0, 0(r5)       ; *buf = 0;
        mr      r3, r4          ; return retval;
        blr