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#include <arpa/inet.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <da.h>
#include <mbstring.h>
#include "assembler.h"
#include "cerr.h"
#include "common.h"
#include "macros.h"
#include "parser.h"
#define E_LEXISTS "label has already been declared"
#define E_LNEXISTS "label hasn’t been declared yet"
struct label {
uint16_t addr;
struct u8view sv;
};
struct labels {
struct label *buf;
size_t len, cap;
};
static void pushlabel(struct labels *, struct label);
static uint16_t getaddr(struct raw_addr);
static struct label *getlabel(struct u8view);
static size_t i;
static struct labels locals, globals;
struct label *
getlabel(struct u8view sv)
{
struct labels *xs = sv.p[0] == '.' ? &locals : &globals;
da_foreach (xs, x) {
if (u8eq(x->sv, sv))
return x;
}
return nullptr;
}
uint16_t
getaddr(struct raw_addr a)
{
struct label *lbl;
if (!a.label)
return a.val;
/* The first 0x200 is reserved for the interpreter, so we need to offset
labels that aren’t integer-literals by that. */
if (lbl = getlabel(a.sv))
return lbl->addr + 0x200;
DIE_AT_POS_WITH_CODE(a.sv, a.sv.p, E_LNEXISTS);
}
void
pushlabel(struct labels *dst, struct label lbl)
{
if (getlabel(lbl.sv))
DIE_AT_POS_WITH_CODE(lbl.sv, lbl.sv.p, E_LEXISTS);
dapush(dst, lbl);
}
void
assemble(FILE *stream, struct ast ast)
{
#define PUT(X) \
do { \
uint16_t __x = htons(X); \
fwrite(&__x, 1, sizeof(__x), stream); \
} while (false)
bool pad = false;
da_foreach (&ast, node) {
assume(node->kind == D_LABEL || node->kind == D_INSTR);
if (node->kind == D_LABEL) {
struct label lbl = {
.addr = i,
.sv = node->name,
};
pushlabel(node->name.p[0] == '.' ? &locals : &globals, lbl);
} else
i += node->instr.kind == I_DB ? node->instr.len : 2;
}
da_foreach (&ast, node) {
if (node->kind == D_LABEL)
continue;
assume(node->kind == D_INSTR);
/* Instructions need to be 0-padded so they appear on an even byte
boundary. */
if (node->instr.kind != I_DB && pad) {
putchar(0);
pad = false;
}
switch (node->instr.kind) {
case I_ADD_I_VX:
PUT(0xF01E | (node->instr.args[0].val << 8));
break;
case I_ADD_VX_B:
PUT(0x7000 | (node->instr.args[0].val << 8)
| node->instr.args[1].val);
break;
case I_ADD_VX_VY:
PUT(0x8004 | (node->instr.args[0].val << 8)
| node->instr.args[1].val << 4);
break;
case I_AND:
PUT(0x8002 | (node->instr.args[0].val << 8)
| node->instr.args[1].val << 4);
break;
case I_BCD:
PUT(0xF033 | (node->instr.args[0].val << 8));
break;
case I_CALL:
PUT(0x2000 | getaddr(node->instr.args[0]));
break;
case I_CLS:
PUT(0x00E0);
break;
case I_DB:
da_foreach (&node->instr, byte)
fputc(*byte, stream);
if (node->instr.len & 1)
pad = !pad;
break;
case I_DRW:
PUT(0xD000 | (node->instr.args[0].val << 8)
| (node->instr.args[1].val << 4) | node->instr.args[2].val);
break;
case I_HEX:
PUT(0xF029 | (node->instr.args[0].val << 8));
break;
case I_JP_A:
PUT(0x1000 | getaddr(node->instr.args[0]));
break;
case I_JP_V0_A:
PUT(0xB000 | getaddr(node->instr.args[0]));
break;
case I_LD_DT:
PUT(0xF015 | (node->instr.args[0].val << 8));
break;
case I_LD_I:
PUT(0xA000 | getaddr(node->instr.args[0]));
break;
case I_LD_ST:
PUT(0xF018 | (node->instr.args[0].val << 8));
break;
case I_LD_VX_B:
PUT(0x6000 | (node->instr.args[0].val << 8)
| node->instr.args[1].val);
break;
case I_LD_VX_DT:
PUT(0xF007 | (node->instr.args[0].val << 8));
break;
case I_LD_VX_K:
PUT(0xF00A | (node->instr.args[0].val << 8));
break;
case I_LD_VX_VY:
PUT(0x8000 | (node->instr.args[0].val << 8)
| node->instr.args[1].val << 4);
break;
case I_OR:
PUT(0x8001 | (node->instr.args[0].val << 8)
| node->instr.args[1].val << 4);
break;
case I_RET:
PUT(0x00EE);
break;
case I_RND:
PUT(0xC000 | (node->instr.args[0].val << 8)
| node->instr.args[1].val);
break;
case I_RSTR:
PUT(0xF065 | (node->instr.args[0].val << 8));
break;
case I_SE_VX_B:
PUT(0x3000 | (node->instr.args[0].val << 8)
| node->instr.args[1].val);
break;
case I_SE_VX_VY:
PUT(0x5000 | (node->instr.args[0].val << 8)
| node->instr.args[1].val << 4);
break;
case I_SHL:
PUT(0x800E | (node->instr.args[0].val << 8));
break;
case I_SHR:
PUT(0x8006 | (node->instr.args[0].val << 8));
break;
case I_SKNP:
PUT(0xE0A1 | (node->instr.args[0].val << 8));
break;
case I_SKP:
PUT(0xE09E | (node->instr.args[0].val << 8));
break;
case I_SNE_VX_B:
PUT(0x4000 | (node->instr.args[0].val << 8)
| node->instr.args[1].val);
break;
case I_SNE_VX_VY:
PUT(0x9000 | (node->instr.args[0].val << 8)
| node->instr.args[1].val << 4);
break;
case I_STOR:
PUT(0xF055 | (node->instr.args[0].val << 8));
break;
case I_SUB:
PUT(0x8005 | (node->instr.args[0].val << 8)
| node->instr.args[1].val << 4);
break;
case I_SUBN:
PUT(0x8007 | (node->instr.args[0].val << 8)
| node->instr.args[1].val << 4);
break;
case I_SYS:
PUT(getaddr(node->instr.args[0]));
break;
case I_XOR:
PUT(0x8003 | (node->instr.args[0].val << 8)
| node->instr.args[1].val << 4);
break;
}
}
if (pad)
putchar(0);
locals.len = 0;
#undef PUT
}
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