string.c

////////////////////////////////////////////////////////////////////
//
// Filename: 	string.c
//
// Project:	CMod S6 System on a Chip, ZipCPU demonstration project
//
// Purpose:	To provide *some* of the C-library's capabilities, without
//		using perfectly optimal functions--but rather simple things that
//	can be easily tested and debugged.
//
// Creator:	Dan Gisselquist, Ph.D.
//		Gisselquist Technology, LLC
//
////////////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2017, Gisselquist Technology, LLC
//
// This program is free software (firmware): you can redistribute it and/or
// modify it under the terms of  the GNU General Public License as published
// by the Free Software Foundation, either version 3 of the License, or (at
// your option) any later version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY 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.  (It's in the $(ROOT)/doc directory.  Run make with no
// target there if the PDF file isn't present.)  If not, see
// <http://www.gnu.org/licenses/> for a copy.
//
// License:	GPL, v3, as defined and found on www.gnu.org,
//		http://www.gnu.org/licenses/gpl.html
//
//
////////////////////////////////////////////////////////////////////////////////
//
//
#include "string.h"

char *
strcpy(char *dst, const char *src) {
	char	v, *d = dst;
	do {
		*dst++ = (v = *src++);
	} while(v);

	return d;
}

char *
strcat(char *dst, const char *src) {
	char	v, *d = dst;
	do {
		v = *dst++;
	} while(v);

	dst--;
	strcpy(dst, src);

	return d;
}

#ifdef	C_STRING_FNS
size_t
strlen(const char *str) {
	size_t	ln = 0;
	while(*str++)
		ln++;
	return ln;
}
#else
asm("\t.section\t.text\n"
	"\t.global\tstrlen\n"
"strlen:\n"
	"\tMOV\tR1,R2\n"
	"\tCLR\tR1\n"
".Lstrlen_loop:\n"
	"\tLB\t(R2),R3\n"
	"\tCMP\t0,R3\n"
	"\tRTN.Z\n"
	"\tADD\t1,R2\n"
	"\tADD\t1,R1\n"
	"\tBRA\t.Lstrlen_loop\n");
#endif

void	*memcpy(void *dest, const void *src, size_t ln) {
	char	*d = dest; const char *s = src;
	if (((((unsigned)d ^ (unsigned)s)&3)==0)&&(ln>4)) {
		// Source and destination are aligned with each other

		// Align them to a word boundary
		int n = (3-(((unsigned)d)&3));
		ln -= n;
		while(n>0) {
			*d++ = *s++; n--;
		}

		int *id = (int *)d;
		const int *is = (const int *)s;
		while(ln >= 4) {
			*id++ = *is++; ln-=4;
		} d = (char *)id; s = (const char *)is;
	}

	while(ln > 0) {
		*d++ = *s++; ln--;
	} return dest;
}

string.s

	.file	"string.c"
	.section	.text
	.global	strlen
strlen:
	MOV	R1,R2
	CLR	R1
.Lstrlen_loop:
	LB	(R2),R3
	CMP	0,R3
	RTN.Z
	ADD	1,R2
	ADD	1,R1
	BRA	.Lstrlen_loop

	.text
	.align	2
	.global	strcpy
	.type	strcpy, @function
strcpy:
	MOV	R1,R3
.L2:
	ADD	1,R3	; addsi3
	ADD	1,R2	; addsi3
	LB	-1(R2),R4	; Zero-Extend:QI
	SB	R4,-1(R3)
	CMP	0,R4
	BNZ	.L2
	RETN
	.size	strcpy, .-strcpy
	.align	2
	.global	strcat
	.type	strcat, @function
strcat:
	MOV	R1,R3
	BRA	.L5
.L7:
.L5:
	ADD	1,R3	; addsi3_raw
	LB	-1(R3),R4	; Zero-Extend:QI
	CMP	0,R4
	BNZ	.L7
.L6:
	ADD	1,R2	; addsi3
	LB	-1(R2),R4	; Zero-Extend:QI
	SB	R4,-1(R3)
	CMP	0,R4
	RETN.Z
	MOV	1(R3),R3
	BRA	.L6
	.size	strcat, .-strcat
	.align	2
	.global	memcpy
	.type	memcpy, @function
memcpy:
	SUB	24,SP	; subsi3
	SW	R5,(SP)
	SW	R6,4(SP)
	SW	R7,8(SP)
	SW	R8,12(SP)
	SW	R9,16(SP)
	SW	R10,20(SP)
	MOV	R2,R4
	XOR	R1,R4	; xorsi3
	TEST	3,R4
	LDI	0,R4
	LDI.Z	1,R4	; cmov
	CMP	5,R3
	LDI	0,R5
	LDI.NC	1,R5	; cmov
	TEST	R5,R4
	BNZ	.L11
	MOV	R1,R4
.L16:
	CMP	0,R3
	BNZ	.L12
	BRA	.L30
.L11:
	MOV	R1,R4
	XOR	-1,R4	; xorsi3
	AND	3,R4	; andsi3
	SUB	R4,R3	; subsi3_raw
	CMP	0,R4
	BZ	.L25
	LB	(R2),R5	; Zero-Extend:QI
	SB	R5,(R1)
	MOV	R4,R5
	ADD	-1,R5	; addsi3_raw
	BZ	.L14
	LB	1(R2),R8	; Zero-Extend:QI
	SB	R8,1(R1)
	CMP	2,R4
	[NZ] LB	2(R2),R10	; Zero-Extend:QI
	[NZ] SB	R10,2(R1)
.L14:
	ADD	R4,R2	; addsi3
	MOV	R1,R5
	ADD	R4,R5	; addsi3
	MOV	R5,R4
	BRA	.L13
.L25:
	MOV	R1,R4
.L13:
	CMP	4,R3
	BC	.L26
	MOV	R2,R7
	MOV	R4,R6
	MOV	R3,R5
.L15:
	ADD	4,R6	; addsi3
	LW	(R7),R8
	ADD	4,R7	; addsi3_raw
	SW	R8,-4(R6)
	ADD	-4,R5	; addsi3_raw
	CMP	4,R5
	BNC	.L15
	MOV	R3,R5
	ADD	-4,R5	; addsi3
	AND	-4,R5	; andsi3
	ADD	4,R5	; addsi3
	AND	3,R3	; andsi3
	ADD	R5,R2	; addsi3
	ADD	R5,R4	; addsi3
	BRA	.L16
.L26:
.L12:
	MOV	R2,R5
	ADD	4,R5	; addsi3_raw
	CMP	R5,R4
	LDI	0,R5
	LDI.NC	1,R5	; cmov
	MOV	R4,R6
	ADD	4,R6	; addsi3_raw
	CMP	R6,R2
	OR.NC	1,R5	; cior
	MOV	R5,R6
	CMP	10,R3
	LDI	0,R5
	LDI.NC	1,R5	; cmov
	AND	R6,R5	; andsi3
	MOV	R5,R6
	MOV	R4,R5
	OR	R2,R5	; iorsi3
	TEST	3,R5
	LDI	0,R5
	LDI.Z	1,R5	; cmov
	TEST	R6,R5
	BZ	.L17
	MOV	R3,R5
	ADD	-4,R5	; addsi3
	LSR	2,R5	; lshrsi3
	ADD	1,R5	; addsi3
	MOV	R5,R9
	LSL	2,R9	; ashlsi3
	MOV	R2,R8
	MOV	R4,R7
	LDI	0,R6
.L18:
	LW	(R8),R10
	SW	R10,(R7)
	ADD	1,R6	; addsi3
	ADD	4,R8	; addsi3
	ADD	4,R7	; addsi3_raw
	CMP	R5,R6
	BC	.L18
	BRA	.L40
.L21:
	LB	2(R2),R2	; Zero-Extend:QI
	SB	R2,2(R4)
	BRA	.L30
.L40:
	MOV	R3,R5
	SUB	R9,R5	; subsi3
	ADD	R9,R4	; addsi3
	ADD	R9,R2	; addsi3_raw
	CMP	R3,R9
	BZ	.L30
	LB	(R2),R3	; Zero-Extend:QI
	SB	R3,(R4)
	MOV	R5,R3
	ADD	-1,R3	; addsi3_raw
	BZ	.L30
	LB	1(R2),R8	; Zero-Extend:QI
	SB	R8,1(R4)
	CMP	2,R5
	BNZ	.L21
	BRA	.L30
.L17:
	MOV	R4,R10
	ADD	R3,R10	; addsi3
	MOV	R10,R3
.L23:
	ADD	1,R4	; addsi3
	ADD	1,R2	; addsi3
	LB	-1(R2),R5	; Zero-Extend:QI
	SB	R5,-1(R4)
	CMP	R3,R4
	BNZ	.L23
.L30:
	LW	(SP),R5
	LW	4(SP),R6
	LW	8(SP),R7
	LW	12(SP),R8
	LW	16(SP),R9
	LW	20(SP),R10
	ADD	24,SP	; addsi3
	RETN
	.size	memcpy, .-memcpy
	.ident	"GCC: (zip-gcc-170306) 6.2.0"