/* Tiny printf routine for use with sdcc/mcs51
 * Copyright (c) 2004, Paul Stoffregen, paul@pjrc.com
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

/*
 * This tiny printf uses minimal code space, and it is fully reentrant
 * and register bank neutral (usually safe to call from within an
 * interrupt routine).  Code size is under 270 bytes.  Only one library
 * function is called (_gptrget, 41 bytes), in addition to calls to
 * putchar().
 * 
 * Five simple formats are supported
 *
 *	%d	signed 16 bit integer decimal (-32768 to 32767)
 *	%u	unsigned 16 bit integer decimal (0 to 65535)
 *	%s	string, takes a 24 bit generic pointer
 *	%c	character.  You must explicitly cast to char in SDCC
 *	%x	16 bit integer in hex (0 to FFFF)
 *
 * For a more complete printf that supports longs, floating point and
 * field width, try using printf_fast() or printf_large().
 */	


// This removes the negative number code, causing "%d" to be the same
// as "%u".  If you don't care about printing negative numbers, this
// will save 21 bytes of code.
//#define ALWAYS_PRINT_UNSIGNED

// Directly output characters to the serial port using simple polling,
// rather than calling putchar().  This saves 14 bytes, plus the size
// of putchar.
//#define DIRECT_SERIAL_OUTPUT



/* extern void putchar(char ); */


#define print_zero_flag PSW.5


#if !defined(SDCC_mcs51) || defined(SDCC_USE_XSTACK) || defined(_SDCC_NO_ASM_LIB_FUNCS)
// Does printf_tiny really work on ds390 and ds400?
// If it does, enable them in the line above
#if defined(SDCC_USE_XSTACK)
#warning "printf_tiny not built, does not support --xstack"
#elif defined(_SDCC_NO_ASM_LIB_FUNCS)
#warning "printf_tiny not built, _SDCC_NO_ASM_LIB_FUNCS defined"
#endif
#else // defines are compatible with printf_tiny



void printf_tiny(code char *fmt, ...) reentrant
{
	fmt;	/* suppress unreferenced variable warning */

	_asm

printf_begin:
	mov	a, _bp		// r0 will point to va_args (stack)
	add	a, #253
	mov	r0, a		// r0 points to MSB of fmt
	mov	dph, @r0
	dec	r0
	mov	dpl, @r0	// dptr has address of fmt
	dec	r0


printf_main_loop:
	clr	a
	movc	a, @a+dptr	// get next byte of fmt string
	inc	dptr
	add	a, #256 - 37
	jz	printf_format	// check for '%'
	add	a, #37
	jz	printf_end_h
	lcall	printf_putchar
	sjmp	printf_main_loop
printf_end_h:
	ljmp	printf_end


printf_format:
	setb	print_zero_flag
	clr	a
	movc	a, @a+dptr	// get next byte of data format
	inc	dptr
	push	dph
	push	dpl


printf_format_s:
	//cjne	a, #'s', printf_format_c
	cjne	a, #115, printf_format_c
printf_string:
	/* print a string... just grab each byte with __gptrget */
	/* the user much pass a 24 bit generic pointer */
	mov	b, @r0		// b has type of address (generic *)
	dec	r0
	mov	dph, @r0
	dec	r0
	mov	dpl, @r0	// dptr has address of user's string
	dec	r0
printf_str_loop:
	lcall	__gptrget
	jz	printf_format_done
	inc	dptr
	lcall	printf_putchar
	sjmp	printf_str_loop


printf_format_c:
	//cjne	a, #'c', printf_format_d
	cjne	a, #99, printf_format_d
	mov	a, @r0		// Acc has the character to print
	dec	r0
	lcall	printf_putchar
	sjmp	printf_format_done


printf_format_d:
	//cjne	a, #'d', printf_format_u
	cjne	a, #100, printf_format_u
#ifndef ALWAYS_PRINT_UNSIGNED
	mov	a, @r0
	jnb	acc.7, printf_uint
	dec	r0
	mov	a, @r0
	cpl	a
	add	a, #1
	mov	@r0, a
	inc	r0
	mov	a, @r0
	cpl	a
	addc	a, #0
	mov	@r0, a
	//mov	a, #'-'
	mov	a, #45
	lcall	printf_putchar
#endif
	sjmp	printf_uint


printf_format_x:
	//cjne	a, #'x', printf_format_u
	cjne	a, #120, printf_format_u
	mov	dph, @r0
	dec	r0
	mov	dpl, @r0
	dec	r0
	clr	a
printf_hex:
	lcall	printf_phex_lsn
	mov	a, dph
	lcall	printf_phex_msn
	mov	a, dph
	lcall	printf_phex_lsn
	mov	a, dpl
	lcall	printf_phex_msn
	mov	a, dpl
	lcall	printf_phex_lsn
	jnb	print_zero_flag, printf_format_done
	//mov	a, #'0'
	mov	a, #48
	lcall	printf_putchar
printf_format_done:
	pop	dpl
	pop	dph
	ljmp	printf_main_loop


printf_format_u:
	//cjne	a, #'u', printf_format_done
	cjne	a, #117, printf_format_done
printf_uint:
	mov	a, @r0
	mov	r2, a
	dec	r0
	mov	a, @r0
	mov	r1, a
	dec	r0
printf_int2bcd:
	mov	r4, #16
	mov	r5, #39
	lcall	div_by_sub
	mov	r7, a
	mov	r4, #232
	mov	r5, #3
	lcall	div_by_sub
	swap	a
	mov	dph, a
	mov	r4, #100
	mov	r5, #0
	lcall	div_by_sub
	orl	dph, a
	mov	a, r1
	mov	b, #10
	div	ab
	swap	a
	orl	a, b
	mov	dpl, a
	mov	a, r7
	sjmp	printf_hex


	// Divide r2/r1 by r5/r4 using successive subtraction
	// returns quotient in r2/r1 and remainder in acc.
div_by_sub:
	mov     r3, #0
div_by_sub_loop:
	inc     r3
        clr     c
        mov     a, r1
        subb    a, r4
        mov     r1, a
        mov     a, r2
        subb    a, r5
        mov     r2, a
        jnc     div_by_sub_loop
        dec     r3
        mov     a, r1
        add     a, r4
        mov     r1, a
        mov     a, r2
        addc    a, r5
        mov     r2, a
        mov     a, r3
        ret


	/* print a hex digit, either upper 4 bit (msn) or lower 4 bits (lsn) */
printf_phex_msn:
	swap	a
printf_phex_lsn:
	anl	a, #15
	jnz	printf_phex_ok
	jb	print_zero_flag, printf_ret
printf_phex_ok:
	clr	print_zero_flag
	add	a, #0x90
	da	a
	addc    a, #0x40
	da	a
printf_putchar:
#ifdef DIRECT_SERIAL_OUTPUT
	jnb	ti, printf_putchar
	clr	ti
	mov	sbuf, a
#else
	push	dph
	push	dpl
	push	b
	mov	dpl, a
	mov	a, r0
	push	acc
	lcall	_putchar
	pop	acc
	mov	r0, a
	pop	b
	pop	dpl
	pop	dph
#endif
printf_ret:
	ret


printf_end:
	_endasm;
}


#endif // defines compatible with printf_tiny

