function codegen_aop_method (binop, op, xtype)
%CODEGEN_AOP_METHOD create a function to compute C(:,:)+=A
%
% codegen_aop_method (binop, op, xtype)

% SuiteSparse:GraphBLAS, Timothy A. Davis, (c) 2017-2025, All Rights Reserved.
% SPDX-License-Identifier: Apache-2.0

% determine type of z, x, and y from xtype and binop
switch (binop)
    case { 'eq', 'ne', 'gt', 'lt', 'ge', 'le' }
        % GrB_LT_* and related operators are TxT -> bool
        ztype = 'bool' ;
        ytype = xtype ;
    case { 'cmplx' }
        % GxB_CMPLX_* are TxT -> (complex T)
        if (isequal (xtype, 'float'))
            ztype = 'GxB_FC32_t' ;
        else
            ztype = 'GxB_FC64_t' ;
        end
        ytype = xtype ;
    case { 'bshift' }
        % z = bitshift (x,y): y is always int8
        ztype = xtype ;
        ytype = 'int8_t' ;
    otherwise
        % all other operators: z, x, and y have the same type
        ztype = xtype ;
        ytype = xtype ;
end

if (~isequal (xtype, ztype) || isequal (binop, 'first'))
    % the type of x and z must match, and the operator must not be 'first'
    return
end

f = fopen ('control.m4', 'w') ;
fprintf (f, 'm4_divert(-1)\n') ;

% no code is generated for the ANY operator (SECOND is used in its place)
assert (~isequal (binop, 'any')) ;

[fname, unsigned, bits] = codegen_type (xtype) ;
codegen_type_enabled (f, fname) ;

name = sprintf ('%s_%s', binop, fname) ;

% function names
fprintf (f, 'm4_define(`_subassign_23'', `_subassign_23__%s'')\n', name) ;
fprintf (f, 'm4_define(`_subassign_22'', `_subassign_22__%s'')\n', name) ;

fprintf (f, 'm4_define(`GB_ztype'',  `#define GB_Z_TYPE %s'')\n', ztype) ;
fprintf (f, 'm4_define(`GB_xtype'',  `#define GB_X_TYPE %s'')\n', xtype) ;
fprintf (f, 'm4_define(`GB_ytype'',  `#define GB_Y_TYPE %s'')\n', ytype) ;
fprintf (f, 'm4_define(`GB_ctype'',  `#define GB_C_TYPE %s'')\n', ztype) ;
fprintf (f, 'm4_define(`GB_atype'',  `#define GB_A_TYPE %s'')\n', ytype) ;
fprintf (f, 'm4_define(`GB_declarec'', `#define GB_DECLAREC(cwork) %s cwork'')\n', ztype) ;

%{
% C_dense_update: operators z=f(x,y) where ztype and xtype match, and binop is not 'first'
if (isequal (xtype, ztype) && ~isequal (binop, 'first'))
    % enable C dense update
    fprintf (f, 'm4_define(`if_C_dense_update'', `0'')\n') ;
else
    % disable C dense update
    fprintf (f, 'm4_define(`if_C_dense_update'', `-1'')\n') ;
end
%}

% to get an entry from A and cast to ywork (but no typecasting here)
if (isequal (binop, 'first') || isequal (binop, 'pair'))
    % value of A is ignored for the FIRST, PAIR, and positional operators
    gb_copy_aij_to_ywork = '' ;
    fprintf (f, 'm4_define(`GB_declarey'', `#define GB_DECLAREY(ywork)'')\n') ;
else
    gb_copy_aij_to_ywork = sprintf (' ywork = Ax [(A_iso) ? 0 : (pA)]') ;
    fprintf (f, 'm4_define(`GB_declarey'', `#define GB_DECLAREY(ywork) %s ywork'')\n', ytype) ;
end
fprintf (f, 'm4_define(`GB_copy_aij_to_ywork'', `#define GB_COPY_aij_to_ywork(ywork,Ax,pA,A_iso)%s'')\n', gb_copy_aij_to_ywork) ;

% to copy a scalar into C (no typecasting)
fprintf (f, 'm4_define(`GB_copy_cwork_to_c'', `#define GB_COPY_cwork_to_C(Cx,pC,cwork,C_iso) Cx [pC] = cwork'')\n') ;

% to copy an entry from A to C (with typecasting)
if (isequal (ytype, 'GxB_FC32_t') && isequal (ztype, 'bool'))
    a2c = '((GB_crealf (Ax [pA]) != 0) || (GB_cimagf (Ax [pA]) != 0))' ;
elseif (isequal (ytype, 'GxB_FC64_t') && isequal (ztype, 'bool'))
    a2c = '((GB_creal (Ax [pA]) != 0) || (GB_cimag (Ax [pA]) != 0))' ;
elseif (isequal (ytype, 'float') && isequal (ztype, 'GxB_FC32_t'))
    a2c = '(GJ_CMPLX32 (Ax [pA], 0))' ;
elseif (isequal (ytype, 'double') && isequal (ztype, 'GxB_FC64_t'))
    a2c = '(GJ_CMPLX64 (Ax [pA], 0))' ;
elseif (isequal (ytype, xtype))
    a2c = sprintf ('Ax [pA]') ;
else
    % use ANSI C typecasting
    a2c = sprintf ('((%s) Ax [pA])', ytype) ;
end
fprintf (f, 'm4_define(`GB_copy_aij_to_c'', `#define GB_COPY_aij_to_C(Cx,pC,Ax,pA,A_iso,cwork,C_iso) Cx [pC] = (A_iso) ? cwork : %s'')\n', a2c) ;
a2c = strrep (a2c, 'pA', 'A_iso ? 0 : (pA)') ;
fprintf (f, 'm4_define(`GB_copy_aij_to_cwork'', `#define GB_COPY_aij_to_cwork(cwork,Ax,pA,A_iso) cwork = %s'')\n', a2c) ;

% mask macro
if (isequal (xtype, 'GxB_FC32_t') || isequal (xtype, 'GxB_FC64_t'))
    asize = sprintf ('sizeof (%s)', xtype) ;
    fprintf (f, 'm4_define(`GB_ax_mask'', `#define GB_AX_MASK(Ax,pA,asize) GB_MCAST (Ax, pA, %s)'')\n', asize) ;
else
    fprintf (f, 'm4_define(`GB_ax_mask'', `#define GB_AX_MASK(Ax,pA,asize) (Ax [pA] != 0)'')\n') ;
end

% type-specific idiv
if (~isempty (strfind (op, 'idiv')))
    if (unsigned)
        op = strrep (op, 'idiv', sprintf ('idiv_uint%d', bits)) ;
    else
        op = strrep (op, 'idiv', sprintf ('idiv_int%d', bits)) ;
    end
end

% create the binary operator
op = strrep (op, 'xarg', 'x') ;
op = strrep (op, 'yarg', 'y') ;
fprintf (f, 'm4_define(`GB_accumop'', `#define GB_ACCUM_OP(z,x,y) z = %s'')\n', op) ;

% create the disable flag
disable = sprintf ('defined(GxB_NO_%s)', upper (binop)) ;
disable = [disable (sprintf (' || defined(GxB_NO_%s)', upper (fname)))] ;
disable = [disable (sprintf (' || defined(GxB_NO_%s_%s)', upper (binop), upper (fname)))] ;
if (isequal (ytype, 'GxB_FC32_t') && ...
    (isequal (binop, 'first') || isequal (binop, 'second')))
    % disable the FIRST_FC32 and SECOND_FC32 binary operators for
    % MS Visual Studio 2019.  These files trigger a bug in the compiler.
    disable = [disable ' || GB_COMPILER_MSC_2019_OR_NEWER'] ;
end
fprintf (f, 'm4_define(`GB_disable'', `#if (%s)\n#define GB_DISABLE 1\n#else\n#define GB_DISABLE 0\n#endif\n'')\n', disable) ;

fprintf (f, 'm4_divert(0)\n') ;
fclose (f) ;

% construct the *.c file
cmd = sprintf ('cat control.m4 Generator/GB_aop.c | m4 -P | awk -f codegen_blank.awk > ../../FactoryKernels/GB_aop__%s.c', name) ;
fprintf ('.') ;
system (cmd) ;

% append to the *.h file
system ('cat control.m4 Generator/GB_aop.h | m4 -P | awk -f codegen_blank.awk | grep -v SPDX >> ../../FactoryKernels/GB_aop__include.h') ;

delete ('control.m4') ;

