471 lines
15 KiB
C
471 lines
15 KiB
C
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/*
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** DynASM x86 encoding engine.
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** Copyright (C) 2005-2011 Mike Pall. All rights reserved.
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** Released under the MIT/X license. See dynasm.lua for full copyright notice.
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*/
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#include <stddef.h>
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#include <stdarg.h>
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#include <string.h>
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#include <stdlib.h>
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#define DASM_ARCH "x86"
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#ifndef DASM_EXTERN
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#define DASM_EXTERN(a,b,c,d) 0
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#endif
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/* Action definitions. DASM_STOP must be 255. */
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enum {
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DASM_DISP = 233,
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DASM_IMM_S, DASM_IMM_B, DASM_IMM_W, DASM_IMM_D, DASM_IMM_WB, DASM_IMM_DB,
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DASM_VREG, DASM_SPACE, DASM_SETLABEL, DASM_REL_A, DASM_REL_LG, DASM_REL_PC,
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DASM_IMM_LG, DASM_IMM_PC, DASM_LABEL_LG, DASM_LABEL_PC, DASM_ALIGN,
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DASM_EXTERN, DASM_ESC, DASM_MARK, DASM_SECTION, DASM_STOP
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};
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/* Maximum number of section buffer positions for a single dasm_put() call. */
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#define DASM_MAXSECPOS 25
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/* DynASM encoder status codes. Action list offset or number are or'ed in. */
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#define DASM_S_OK 0x00000000
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#define DASM_S_NOMEM 0x01000000
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#define DASM_S_PHASE 0x02000000
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#define DASM_S_MATCH_SEC 0x03000000
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#define DASM_S_RANGE_I 0x11000000
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#define DASM_S_RANGE_SEC 0x12000000
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#define DASM_S_RANGE_LG 0x13000000
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#define DASM_S_RANGE_PC 0x14000000
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#define DASM_S_RANGE_VREG 0x15000000
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#define DASM_S_UNDEF_L 0x21000000
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#define DASM_S_UNDEF_PC 0x22000000
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/* Macros to convert positions (8 bit section + 24 bit index). */
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#define DASM_POS2IDX(pos) ((pos)&0x00ffffff)
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#define DASM_POS2BIAS(pos) ((pos)&0xff000000)
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#define DASM_SEC2POS(sec) ((sec)<<24)
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#define DASM_POS2SEC(pos) ((pos)>>24)
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#define DASM_POS2PTR(D, pos) (D->sections[DASM_POS2SEC(pos)].rbuf + (pos))
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/* Action list type. */
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typedef const unsigned char *dasm_ActList;
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/* Per-section structure. */
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typedef struct dasm_Section {
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int *rbuf; /* Biased buffer pointer (negative section bias). */
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int *buf; /* True buffer pointer. */
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size_t bsize; /* Buffer size in bytes. */
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int pos; /* Biased buffer position. */
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int epos; /* End of biased buffer position - max single put. */
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int ofs; /* Byte offset into section. */
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} dasm_Section;
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/* Core structure holding the DynASM encoding state. */
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struct dasm_State {
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size_t psize; /* Allocated size of this structure. */
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dasm_ActList actionlist; /* Current actionlist pointer. */
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int *lglabels; /* Local/global chain/pos ptrs. */
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size_t lgsize;
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int *pclabels; /* PC label chains/pos ptrs. */
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size_t pcsize;
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void **globals; /* Array of globals (bias -10). */
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dasm_Section *section; /* Pointer to active section. */
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size_t codesize; /* Total size of all code sections. */
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int maxsection; /* 0 <= sectionidx < maxsection. */
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int status; /* Status code. */
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dasm_Section sections[1]; /* All sections. Alloc-extended. */
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};
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/* The size of the core structure depends on the max. number of sections. */
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#define DASM_PSZ(ms) (sizeof(dasm_State)+(ms-1)*sizeof(dasm_Section))
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/* Initialize DynASM state. */
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void dasm_init(Dst_DECL, int maxsection)
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{
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dasm_State *D;
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size_t psz = 0;
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int i;
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Dst_REF = NULL;
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DASM_M_GROW(Dst, struct dasm_State, Dst_REF, psz, DASM_PSZ(maxsection));
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D = Dst_REF;
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D->psize = psz;
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D->lglabels = NULL;
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D->lgsize = 0;
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D->pclabels = NULL;
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D->pcsize = 0;
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D->globals = NULL;
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D->maxsection = maxsection;
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for (i = 0; i < maxsection; i++) {
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D->sections[i].buf = NULL; /* Need this for pass3. */
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D->sections[i].rbuf = D->sections[i].buf - DASM_SEC2POS(i);
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D->sections[i].bsize = 0;
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D->sections[i].epos = 0; /* Wrong, but is recalculated after resize. */
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}
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}
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/* Free DynASM state. */
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void dasm_free(Dst_DECL)
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{
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dasm_State *D = Dst_REF;
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int i;
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for (i = 0; i < D->maxsection; i++)
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if (D->sections[i].buf)
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DASM_M_FREE(Dst, D->sections[i].buf, D->sections[i].bsize);
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if (D->pclabels) DASM_M_FREE(Dst, D->pclabels, D->pcsize);
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if (D->lglabels) DASM_M_FREE(Dst, D->lglabels, D->lgsize);
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DASM_M_FREE(Dst, D, D->psize);
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}
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/* Setup global label array. Must be called before dasm_setup(). */
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void dasm_setupglobal(Dst_DECL, void **gl, unsigned int maxgl)
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{
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dasm_State *D = Dst_REF;
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D->globals = gl - 10; /* Negative bias to compensate for locals. */
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DASM_M_GROW(Dst, int, D->lglabels, D->lgsize, (10+maxgl)*sizeof(int));
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}
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/* Grow PC label array. Can be called after dasm_setup(), too. */
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void dasm_growpc(Dst_DECL, unsigned int maxpc)
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{
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dasm_State *D = Dst_REF;
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size_t osz = D->pcsize;
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DASM_M_GROW(Dst, int, D->pclabels, D->pcsize, maxpc*sizeof(int));
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memset((void *)(((unsigned char *)D->pclabels)+osz), 0, D->pcsize-osz);
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}
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/* Setup encoder. */
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void dasm_setup(Dst_DECL, const void *actionlist)
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{
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dasm_State *D = Dst_REF;
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int i;
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D->actionlist = (dasm_ActList)actionlist;
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D->status = DASM_S_OK;
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D->section = &D->sections[0];
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memset((void *)D->lglabels, 0, D->lgsize);
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if (D->pclabels) memset((void *)D->pclabels, 0, D->pcsize);
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for (i = 0; i < D->maxsection; i++) {
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D->sections[i].pos = DASM_SEC2POS(i);
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D->sections[i].ofs = 0;
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}
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}
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#ifdef DASM_CHECKS
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#define CK(x, st) \
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do { if (!(x)) { \
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D->status = DASM_S_##st|(int)(p-D->actionlist-1); return; } } while (0)
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#define CKPL(kind, st) \
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do { if ((size_t)((char *)pl-(char *)D->kind##labels) >= D->kind##size) { \
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D->status=DASM_S_RANGE_##st|(int)(p-D->actionlist-1); return; } } while (0)
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#else
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#define CK(x, st) ((void)0)
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#define CKPL(kind, st) ((void)0)
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#endif
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/* Pass 1: Store actions and args, link branches/labels, estimate offsets. */
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void dasm_put(Dst_DECL, int start, ...)
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{
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va_list ap;
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dasm_State *D = Dst_REF;
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dasm_ActList p = D->actionlist + start;
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dasm_Section *sec = D->section;
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int pos = sec->pos, ofs = sec->ofs, mrm = 4;
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int *b;
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if (pos >= sec->epos) {
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DASM_M_GROW(Dst, int, sec->buf, sec->bsize,
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sec->bsize + 2*DASM_MAXSECPOS*sizeof(int));
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sec->rbuf = sec->buf - DASM_POS2BIAS(pos);
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sec->epos = (int)sec->bsize/sizeof(int) - DASM_MAXSECPOS+DASM_POS2BIAS(pos);
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}
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b = sec->rbuf;
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b[pos++] = start;
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va_start(ap, start);
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while (1) {
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int action = *p++;
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if (action < DASM_DISP) {
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ofs++;
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} else if (action <= DASM_REL_A) {
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int n = va_arg(ap, int);
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b[pos++] = n;
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switch (action) {
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case DASM_DISP:
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if (n == 0) { if ((mrm&7) == 4) mrm = p[-2]; if ((mrm&7) != 5) break; }
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case DASM_IMM_DB: if (((n+128)&-256) == 0) goto ob;
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case DASM_REL_A: /* Assumes ptrdiff_t is int. !x64 */
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case DASM_IMM_D: ofs += 4; break;
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case DASM_IMM_S: CK(((n+128)&-256) == 0, RANGE_I); goto ob;
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case DASM_IMM_B: CK((n&-256) == 0, RANGE_I); ob: ofs++; break;
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case DASM_IMM_WB: if (((n+128)&-256) == 0) goto ob;
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case DASM_IMM_W: CK((n&-65536) == 0, RANGE_I); ofs += 2; break;
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case DASM_SPACE: p++; ofs += n; break;
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case DASM_SETLABEL: b[pos-2] = -0x40000000; break; /* Neg. label ofs. */
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case DASM_VREG: CK((n&-8) == 0 && (n != 4 || (*p&1) == 0), RANGE_VREG);
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if (*p++ == 1 && *p == DASM_DISP) mrm = n; continue;
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}
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mrm = 4;
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} else {
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int *pl, n;
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switch (action) {
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case DASM_REL_LG:
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case DASM_IMM_LG:
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n = *p++; pl = D->lglabels + n;
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if (n <= 246) { CKPL(lg, LG); goto putrel; } /* Bkwd rel or global. */
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pl -= 246; n = *pl;
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if (n < 0) n = 0; /* Start new chain for fwd rel if label exists. */
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goto linkrel;
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case DASM_REL_PC:
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case DASM_IMM_PC: pl = D->pclabels + va_arg(ap, int); CKPL(pc, PC);
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putrel:
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n = *pl;
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if (n < 0) { /* Label exists. Get label pos and store it. */
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b[pos] = -n;
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} else {
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linkrel:
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b[pos] = n; /* Else link to rel chain, anchored at label. */
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*pl = pos;
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}
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pos++;
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ofs += 4; /* Maximum offset needed. */
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if (action == DASM_REL_LG || action == DASM_REL_PC)
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b[pos++] = ofs; /* Store pass1 offset estimate. */
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break;
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case DASM_LABEL_LG: pl = D->lglabels + *p++; CKPL(lg, LG); goto putlabel;
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case DASM_LABEL_PC: pl = D->pclabels + va_arg(ap, int); CKPL(pc, PC);
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putlabel:
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n = *pl; /* n > 0: Collapse rel chain and replace with label pos. */
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while (n > 0) { int *pb = DASM_POS2PTR(D, n); n = *pb; *pb = pos; }
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*pl = -pos; /* Label exists now. */
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b[pos++] = ofs; /* Store pass1 offset estimate. */
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break;
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case DASM_ALIGN:
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ofs += *p++; /* Maximum alignment needed (arg is 2**n-1). */
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b[pos++] = ofs; /* Store pass1 offset estimate. */
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break;
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case DASM_EXTERN: p += 2; ofs += 4; break;
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case DASM_ESC: p++; ofs++; break;
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case DASM_MARK: mrm = p[-2]; break;
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case DASM_SECTION:
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n = *p; CK(n < D->maxsection, RANGE_SEC); D->section = &D->sections[n];
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case DASM_STOP: goto stop;
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}
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}
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}
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stop:
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va_end(ap);
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sec->pos = pos;
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sec->ofs = ofs;
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}
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#undef CK
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/* Pass 2: Link sections, shrink branches/aligns, fix label offsets. */
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int dasm_link(Dst_DECL, size_t *szp)
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{
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dasm_State *D = Dst_REF;
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int secnum;
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int ofs = 0;
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#ifdef DASM_CHECKS
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*szp = 0;
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if (D->status != DASM_S_OK) return D->status;
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{
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int pc;
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for (pc = 0; pc*sizeof(int) < D->pcsize; pc++)
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if (D->pclabels[pc] > 0) return DASM_S_UNDEF_PC|pc;
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}
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#endif
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{ /* Handle globals not defined in this translation unit. */
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int idx;
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for (idx = 10; idx*sizeof(int) < D->lgsize; idx++) {
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int n = D->lglabels[idx];
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/* Undefined label: Collapse rel chain and replace with marker (< 0). */
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while (n > 0) { int *pb = DASM_POS2PTR(D, n); n = *pb; *pb = -idx; }
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}
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}
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/* Combine all code sections. No support for data sections (yet). */
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for (secnum = 0; secnum < D->maxsection; secnum++) {
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dasm_Section *sec = D->sections + secnum;
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int *b = sec->rbuf;
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int pos = DASM_SEC2POS(secnum);
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int lastpos = sec->pos;
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while (pos != lastpos) {
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dasm_ActList p = D->actionlist + b[pos++];
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while (1) {
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int op, action = *p++;
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switch (action) {
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case DASM_REL_LG: p++; op = p[-3]; goto rel_pc;
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case DASM_REL_PC: op = p[-2]; rel_pc: {
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int shrink = op == 0xe9 ? 3 : ((op&0xf0) == 0x80 ? 4 : 0);
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if (shrink) { /* Shrinkable branch opcode? */
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int lofs, lpos = b[pos];
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if (lpos < 0) goto noshrink; /* Ext global? */
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lofs = *DASM_POS2PTR(D, lpos);
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if (lpos > pos) { /* Fwd label: add cumulative section offsets. */
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int i;
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for (i = secnum; i < DASM_POS2SEC(lpos); i++)
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lofs += D->sections[i].ofs;
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} else {
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lofs -= ofs; /* Bkwd label: unfix offset. */
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}
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lofs -= b[pos+1]; /* Short branch ok? */
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if (lofs >= -128-shrink && lofs <= 127) ofs -= shrink; /* Yes. */
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else { noshrink: shrink = 0; } /* No, cannot shrink op. */
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}
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b[pos+1] = shrink;
|
||
|
|
pos += 2;
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
case DASM_SPACE: case DASM_IMM_LG: case DASM_VREG: p++;
|
||
|
|
case DASM_DISP: case DASM_IMM_S: case DASM_IMM_B: case DASM_IMM_W:
|
||
|
|
case DASM_IMM_D: case DASM_IMM_WB: case DASM_IMM_DB:
|
||
|
|
case DASM_SETLABEL: case DASM_REL_A: case DASM_IMM_PC: pos++; break;
|
||
|
|
case DASM_LABEL_LG: p++;
|
||
|
|
case DASM_LABEL_PC: b[pos++] += ofs; break; /* Fix label offset. */
|
||
|
|
case DASM_ALIGN: ofs -= (b[pos++]+ofs)&*p++; break; /* Adjust ofs. */
|
||
|
|
case DASM_EXTERN: p += 2; break;
|
||
|
|
case DASM_ESC: p++; break;
|
||
|
|
case DASM_MARK: break;
|
||
|
|
case DASM_SECTION: case DASM_STOP: goto stop;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
stop: (void)0;
|
||
|
|
}
|
||
|
|
ofs += sec->ofs; /* Next section starts right after current section. */
|
||
|
|
}
|
||
|
|
|
||
|
|
D->codesize = ofs; /* Total size of all code sections */
|
||
|
|
*szp = ofs;
|
||
|
|
return DASM_S_OK;
|
||
|
|
}
|
||
|
|
|
||
|
|
#define dasmb(x) *cp++ = (unsigned char)(x)
|
||
|
|
#ifndef DASM_ALIGNED_WRITES
|
||
|
|
#define dasmw(x) \
|
||
|
|
do { *((unsigned short *)cp) = (unsigned short)(x); cp+=2; } while (0)
|
||
|
|
#define dasmd(x) \
|
||
|
|
do { *((unsigned int *)cp) = (unsigned int)(x); cp+=4; } while (0)
|
||
|
|
#else
|
||
|
|
#define dasmw(x) do { dasmb(x); dasmb((x)>>8); } while (0)
|
||
|
|
#define dasmd(x) do { dasmw(x); dasmw((x)>>16); } while (0)
|
||
|
|
#endif
|
||
|
|
|
||
|
|
/* Pass 3: Encode sections. */
|
||
|
|
int dasm_encode(Dst_DECL, void *buffer)
|
||
|
|
{
|
||
|
|
dasm_State *D = Dst_REF;
|
||
|
|
unsigned char *base = (unsigned char *)buffer;
|
||
|
|
unsigned char *cp = base;
|
||
|
|
int secnum;
|
||
|
|
|
||
|
|
/* Encode all code sections. No support for data sections (yet). */
|
||
|
|
for (secnum = 0; secnum < D->maxsection; secnum++) {
|
||
|
|
dasm_Section *sec = D->sections + secnum;
|
||
|
|
int *b = sec->buf;
|
||
|
|
int *endb = sec->rbuf + sec->pos;
|
||
|
|
|
||
|
|
while (b != endb) {
|
||
|
|
dasm_ActList p = D->actionlist + *b++;
|
||
|
|
unsigned char *mark = NULL;
|
||
|
|
while (1) {
|
||
|
|
int action = *p++;
|
||
|
|
int n = (action >= DASM_DISP && action <= DASM_ALIGN) ? *b++ : 0;
|
||
|
|
switch (action) {
|
||
|
|
case DASM_DISP: if (!mark) mark = cp; {
|
||
|
|
unsigned char *mm = mark;
|
||
|
|
if (*p != DASM_IMM_DB && *p != DASM_IMM_WB) mark = NULL;
|
||
|
|
if (n == 0) { int mrm = mm[-1]&7; if (mrm == 4) mrm = mm[0]&7;
|
||
|
|
if (mrm != 5) { mm[-1] -= 0x80; break; } }
|
||
|
|
if (((n+128) & -256) != 0) goto wd; else mm[-1] -= 0x40;
|
||
|
|
}
|
||
|
|
case DASM_IMM_S: case DASM_IMM_B: wb: dasmb(n); break;
|
||
|
|
case DASM_IMM_DB: if (((n+128)&-256) == 0) {
|
||
|
|
db: if (!mark) mark = cp; mark[-2] += 2; mark = NULL; goto wb;
|
||
|
|
} else mark = NULL;
|
||
|
|
case DASM_IMM_D: wd: dasmd(n); break;
|
||
|
|
case DASM_IMM_WB: if (((n+128)&-256) == 0) goto db; else mark = NULL;
|
||
|
|
case DASM_IMM_W: dasmw(n); break;
|
||
|
|
case DASM_VREG: { int t = *p++; if (t >= 2) n<<=3; cp[-1] |= n; break; }
|
||
|
|
case DASM_REL_LG: p++; if (n >= 0) goto rel_pc;
|
||
|
|
b++; n = (int)(ptrdiff_t)D->globals[-n];
|
||
|
|
case DASM_REL_A: rel_a: n -= (int)(ptrdiff_t)(cp+4); goto wd; /* !x64 */
|
||
|
|
case DASM_REL_PC: rel_pc: {
|
||
|
|
int shrink = *b++;
|
||
|
|
int *pb = DASM_POS2PTR(D, n); if (*pb < 0) { n = pb[1]; goto rel_a; }
|
||
|
|
n = *pb - ((int)(cp-base) + 4-shrink);
|
||
|
|
if (shrink == 0) goto wd;
|
||
|
|
if (shrink == 4) { cp--; cp[-1] = *cp-0x10; } else cp[-1] = 0xeb;
|
||
|
|
goto wb;
|
||
|
|
}
|
||
|
|
case DASM_IMM_LG:
|
||
|
|
p++; if (n < 0) { n = (int)(ptrdiff_t)D->globals[-n]; goto wd; }
|
||
|
|
case DASM_IMM_PC: {
|
||
|
|
int *pb = DASM_POS2PTR(D, n);
|
||
|
|
n = *pb < 0 ? pb[1] : (*pb + (int)(ptrdiff_t)base);
|
||
|
|
goto wd;
|
||
|
|
}
|
||
|
|
case DASM_LABEL_LG: {
|
||
|
|
int idx = *p++;
|
||
|
|
if (idx >= 10)
|
||
|
|
D->globals[idx] = (void *)(base + (*p == DASM_SETLABEL ? *b : n));
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
case DASM_LABEL_PC: case DASM_SETLABEL: break;
|
||
|
|
case DASM_SPACE: { int fill = *p++; while (n--) *cp++ = fill; break; }
|
||
|
|
case DASM_ALIGN:
|
||
|
|
n = *p++;
|
||
|
|
while (((cp-base) & n)) *cp++ = 0x90; /* nop */
|
||
|
|
break;
|
||
|
|
case DASM_EXTERN: n = DASM_EXTERN(Dst, cp, p[1], *p); p += 2; goto wd;
|
||
|
|
case DASM_MARK: mark = cp; break;
|
||
|
|
case DASM_ESC: action = *p++;
|
||
|
|
default: *cp++ = action; break;
|
||
|
|
case DASM_SECTION: case DASM_STOP: goto stop;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
stop: (void)0;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
if (base + D->codesize != cp) /* Check for phase errors. */
|
||
|
|
return DASM_S_PHASE;
|
||
|
|
return DASM_S_OK;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Get PC label offset. */
|
||
|
|
int dasm_getpclabel(Dst_DECL, unsigned int pc)
|
||
|
|
{
|
||
|
|
dasm_State *D = Dst_REF;
|
||
|
|
if (pc*sizeof(int) < D->pcsize) {
|
||
|
|
int pos = D->pclabels[pc];
|
||
|
|
if (pos < 0) return *DASM_POS2PTR(D, -pos);
|
||
|
|
if (pos > 0) return -1; /* Undefined. */
|
||
|
|
}
|
||
|
|
return -2; /* Unused or out of range. */
|
||
|
|
}
|
||
|
|
|
||
|
|
#ifdef DASM_CHECKS
|
||
|
|
/* Optional sanity checker to call between isolated encoding steps. */
|
||
|
|
int dasm_checkstep(Dst_DECL, int secmatch)
|
||
|
|
{
|
||
|
|
dasm_State *D = Dst_REF;
|
||
|
|
if (D->status == DASM_S_OK) {
|
||
|
|
int i;
|
||
|
|
for (i = 1; i <= 9; i++) {
|
||
|
|
if (D->lglabels[i] > 0) { D->status = DASM_S_UNDEF_L|i; break; }
|
||
|
|
D->lglabels[i] = 0;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
if (D->status == DASM_S_OK && secmatch >= 0 &&
|
||
|
|
D->section != &D->sections[secmatch])
|
||
|
|
D->status = DASM_S_MATCH_SEC|(int)(D->section-D->sections);
|
||
|
|
return D->status;
|
||
|
|
}
|
||
|
|
#endif
|
||
|
|
|