asmthumb.c 15.2 KB
Newer Older
Damien's avatar
Damien committed
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
#include <stdint.h>
#include <stdio.h>
#include <assert.h>
#include <string.h>

#include "misc.h"
#include "machine.h"
#include "asmthumb.h"

#define UNSIGNED_FIT8(x) (((x) & 0xffffff00) == 0)
#define UNSIGNED_FIT16(x) (((x) & 0xffff0000) == 0)
#define SIGNED_FIT8(x) (((x) & 0xffffff80) == 0) || (((x) & 0xffffff80) == 0xffffff80)
#define SIGNED_FIT9(x) (((x) & 0xffffff00) == 0) || (((x) & 0xffffff00) == 0xffffff00)
#define SIGNED_FIT12(x) (((x) & 0xfffff800) == 0) || (((x) & 0xfffff800) == 0xfffff800)

struct _asm_thumb_t {
    int pass;
    uint code_offset;
    uint code_size;
    byte *code_base;
    byte dummy_data[8];

    int max_num_labels;
    int *label_offsets;
    int num_locals;
    uint push_reglist;
    uint stack_adjust;
};

30
asm_thumb_t *asm_thumb_new(uint max_num_labels) {
Damien's avatar
Damien committed
31
32
33
34
35
36
37
    asm_thumb_t *as;

    as = m_new(asm_thumb_t, 1);
    as->pass = 0;
    as->code_offset = 0;
    as->code_size = 0;
    as->code_base = NULL;
38
39
    as->max_num_labels = max_num_labels;
    as->label_offsets = m_new(int, max_num_labels);
Damien's avatar
Damien committed
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
    as->num_locals = 0;

    return as;
}

void asm_thumb_free(asm_thumb_t *as, bool free_code) {
    if (free_code) {
        m_free(as->code_base);
    }
    /*
    if (as->label != NULL) {
        int i;
        for (i = 0; i < as->label->len; ++i)
        {
            Label *lab = &g_array_index(as->label, Label, i);
            if (lab->unresolved != NULL)
                g_array_free(lab->unresolved, true);
        }
        g_array_free(as->label, true);
    }
    */
    m_free(as);
}

void asm_thumb_start_pass(asm_thumb_t *as, int pass) {
    as->pass = pass;
    as->code_offset = 0;
67
68
    if (pass == ASM_THUMB_PASS_2) {
        memset(as->label_offsets, -1, as->max_num_labels * sizeof(int));
Damien's avatar
Damien committed
69
70
71
72
    }
}

void asm_thumb_end_pass(asm_thumb_t *as) {
73
    if (as->pass == ASM_THUMB_PASS_2) {
Damien's avatar
Damien committed
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
        // calculate size of code in bytes
        as->code_size = as->code_offset;
        as->code_base = m_new(byte, as->code_size);
        printf("code_size: %u\n", as->code_size);
    }

    /*
    // check labels are resolved
    if (as->label != NULL)
    {
        int i;
        for (i = 0; i < as->label->len; ++i)
            if (g_array_index(as->label, Label, i).unresolved != NULL)
                return false;
    }
    */
}

// all functions must go through this one to emit bytes
static byte *asm_thumb_get_cur_to_write_bytes(asm_thumb_t *as, int num_bytes_to_write) {
    //printf("emit %d\n", num_bytes_to_write);
    if (as->pass < ASM_THUMB_PASS_3) {
        as->code_offset += num_bytes_to_write;
        return as->dummy_data;
    } else {
        assert(as->code_offset + num_bytes_to_write <= as->code_size);
        byte *c = as->code_base + as->code_offset;
        as->code_offset += num_bytes_to_write;
        return c;
    }
}

uint asm_thumb_get_code_size(asm_thumb_t *as) {
    return as->code_size;
}

void *asm_thumb_get_code(asm_thumb_t *as) {
    // need to set low bit to indicate that it's thumb code
    return (void *)(((machine_uint_t)as->code_base) | 1);
}

/*
static void asm_thumb_write_byte_1(asm_thumb_t *as, byte b1) {
    byte *c = asm_thumb_get_cur_to_write_bytes(as, 1);
    c[0] = b1;
}
*/

static void asm_thumb_write_op16(asm_thumb_t *as, uint op) {
    byte *c = asm_thumb_get_cur_to_write_bytes(as, 2);
    // little endian
    c[0] = op;
    c[1] = op >> 8;
}

static void asm_thumb_write_op32(asm_thumb_t *as, uint op1, uint op2) {
    byte *c = asm_thumb_get_cur_to_write_bytes(as, 4);
    // little endian, op1 then op2
    c[0] = op1;
    c[1] = op1 >> 8;
    c[2] = op2;
    c[3] = op2 >> 8;
}

/*
#define IMM32_L0(x) ((x) & 0xff)
#define IMM32_L1(x) (((x) >> 8) & 0xff)
#define IMM32_L2(x) (((x) >> 16) & 0xff)
#define IMM32_L3(x) (((x) >> 24) & 0xff)

static void asm_thumb_write_word32(asm_thumb_t *as, int w32) {
    byte *c = asm_thumb_get_cur_to_write_bytes(as, 4);
    c[0] = IMM32_L0(w32);
    c[1] = IMM32_L1(w32);
    c[2] = IMM32_L2(w32);
    c[3] = IMM32_L3(w32);
}
*/

// rlolist is a bit map indicating desired lo-registers
#define OP_PUSH_RLIST(rlolist)      (0xb400 | (rlolist))
#define OP_PUSH_RLIST_LR(rlolist)   (0xb400 | 0x0100 | (rlolist))
#define OP_POP_RLIST(rlolist)       (0xbc00 | (rlolist))
#define OP_POP_RLIST_PC(rlolist)    (0xbc00 | 0x0100 | (rlolist))

#define OP_ADD_SP(num_words) (0xb000 | (num_words))
#define OP_SUB_SP(num_words) (0xb080 | (num_words))

void asm_thumb_entry(asm_thumb_t *as, int num_locals) {
    // work out what to push and how many extra space to reserve on stack
    // so that we have enough for all locals and it's aligned an 8-byte boundary
    uint reglist;
    uint stack_adjust;
    if (num_locals < 0) {
        num_locals = 0;
    }
    // don't ppop r0 because it's used for return value
    switch (num_locals) {
        case 0:
            reglist = 0xf2;
            stack_adjust = 0;
            break;

        case 1:
            reglist = 0xf2;
            stack_adjust = 0;
            break;

        case 2:
            reglist = 0xfe;
            stack_adjust = 0;
            break;

        case 3:
            reglist = 0xfe;
            stack_adjust = 0;
            break;

        default:
            reglist = 0xfe;
            stack_adjust = ((num_locals - 3) + 1) & (~1);
            break;
    }
    asm_thumb_write_op16(as, OP_PUSH_RLIST_LR(reglist));
    if (stack_adjust > 0) {
        asm_thumb_write_op16(as, OP_SUB_SP(stack_adjust));
    }
    as->push_reglist = reglist;
    as->stack_adjust = stack_adjust;
    as->num_locals = num_locals;
}

void asm_thumb_exit(asm_thumb_t *as) {
    if (as->stack_adjust > 0) {
        asm_thumb_write_op16(as, OP_ADD_SP(as->stack_adjust));
    }
    asm_thumb_write_op16(as, OP_POP_RLIST_PC(as->push_reglist));
}

void asm_thumb_label_assign(asm_thumb_t *as, int label) {
214
215
216
217
218
219
220
221
222
    assert(label < as->max_num_labels);
    if (as->pass == ASM_THUMB_PASS_2) {
        // assign label offset
        assert(as->label_offsets[label] == -1);
        as->label_offsets[label] = as->code_offset;
    } else if (as->pass == ASM_THUMB_PASS_3) {
        // ensure label offset has not changed from PASS_2 to PASS_3
        //printf("l%d: (at %d=%ld)\n", label, as->label_offsets[label], as->code_offset);
        assert(as->label_offsets[label] == as->code_offset);
Damien's avatar
Damien committed
223
224
225
    }
}

226
227
228
229
230
static int get_label_dest(asm_thumb_t *as, int label) {
    assert(label < as->max_num_labels);
    return as->label_offsets[label];
}

231
232
233
234
#define OP_MOVS_RLO_I8(rlo_dest, i8_src) (0x2000 | ((rlo_dest) << 8) | (i8_src))

// the i8_src value will be zero extended into the r32 register!
void asm_thumb_movs_rlo_i8(asm_thumb_t *as, uint rlo_dest, int i8_src) {
Damien's avatar
Damien committed
235
    assert(rlo_dest < REG_R8);
236
237
    // movs rlo_dest, #i8_src
    asm_thumb_write_op16(as, OP_MOVS_RLO_I8(rlo_dest, i8_src));
Damien's avatar
Damien committed
238
239
}

240
241
242
243
244
#define OP_MOVW (0xf240)
#define OP_MOVT (0xf2c0)

// if loading lo half with movw, the i16 value will be zero extended into the r32 register!
static void asm_thumb_mov_reg_i16(asm_thumb_t *as, uint mov_op, uint reg_dest, int i16_src) {
Damien's avatar
Damien committed
245
    assert(reg_dest < REG_R15);
246
247
    // mov[wt] reg_dest, #i16_src
    asm_thumb_write_op32(as, mov_op | ((i16_src >> 1) & 0x0400) | ((i16_src >> 12) & 0xf), ((i16_src << 4) & 0x7000) | (reg_dest << 8) | (i16_src & 0xff));
Damien's avatar
Damien committed
248
249
}

250
251
252
// the i16_src value will be zero extended into the r32 register!
void asm_thumb_movw_reg_i16(asm_thumb_t *as, uint reg_dest, int i16_src) {
    asm_thumb_mov_reg_i16(as, OP_MOVW, reg_dest, i16_src);
Damien's avatar
Damien committed
253
254
}

255
256
257
// the i16_src value will be zero extended into the r32 register!
void asm_thumb_movt_reg_i16(asm_thumb_t *as, uint reg_dest, int i16_src) {
    asm_thumb_mov_reg_i16(as, OP_MOVT, reg_dest, i16_src);
Damien's avatar
Damien committed
258
259
260
261
262
263
264
265
266
267
268
269
270
271
}

void asm_thumb_mov_reg_reg(asm_thumb_t *as, uint reg_dest, uint reg_src) {
    uint op_lo;
    if (reg_src < 8) {
        op_lo = reg_src << 3;
    } else {
        op_lo = 0x40 | ((reg_src - 8) << 3);
    }
    if (reg_dest < 8) {
        op_lo |= reg_dest;
    } else {
        op_lo |= 0x80 | (reg_dest - 8);
    }
272
    // mov reg_dest, reg_src
Damien's avatar
Damien committed
273
274
275
    asm_thumb_write_op16(as, 0x4600 | op_lo);
}

276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
#define OP_SUBS_RLO_RLO_I3(rlo_dest, rlo_src, i3_src) (0x1e00 | ((i3_src) << 6) | ((rlo_src) << 3) | (rlo_dest))

void asm_thumb_subs_rlo_rlo_i3(asm_thumb_t *as, uint rlo_dest, uint rlo_src, int i3_src) {
    assert(rlo_dest < REG_R8);
    assert(rlo_src < REG_R8);
    asm_thumb_write_op16(as, OP_SUBS_RLO_RLO_I3(rlo_dest, rlo_src, i3_src));
}

#define OP_CMP_RLO_I8(rlo, i8) (0x2800 | ((rlo) << 8) | (i8))

void asm_thumb_cmp_rlo_i8(asm_thumb_t *as, uint rlo, int i8) {
    assert(rlo < REG_R8);
    asm_thumb_write_op16(as, OP_CMP_RLO_I8(rlo, i8));
}

#define OP_BEQ_N(byte_offset) (0xd000 | (((byte_offset) >> 1) & 0x00ff))
#define OP_BNE_N(byte_offset) (0xd100 | (((byte_offset) >> 1) & 0x00ff))
#define OP_BCS_N(byte_offset) (0xd200 | (((byte_offset) >> 1) & 0x00ff))
#define OP_BCC_N(byte_offset) (0xd300 | (((byte_offset) >> 1) & 0x00ff))
#define OP_BMI_N(byte_offset) (0xd400 | (((byte_offset) >> 1) & 0x00ff))
#define OP_BPL_N(byte_offset) (0xd500 | (((byte_offset) >> 1) & 0x00ff))
#define OP_BVS_N(byte_offset) (0xd600 | (((byte_offset) >> 1) & 0x00ff))
#define OP_BVC_N(byte_offset) (0xd700 | (((byte_offset) >> 1) & 0x00ff))
#define OP_BHI_N(byte_offset) (0xd800 | (((byte_offset) >> 1) & 0x00ff))
#define OP_BLS_N(byte_offset) (0xd900 | (((byte_offset) >> 1) & 0x00ff))
#define OP_BGE_N(byte_offset) (0xda00 | (((byte_offset) >> 1) & 0x00ff))
#define OP_BLT_N(byte_offset) (0xdb00 | (((byte_offset) >> 1) & 0x00ff))
#define OP_BGT_N(byte_offset) (0xdc00 | (((byte_offset) >> 1) & 0x00ff))
#define OP_BLE_N(byte_offset) (0xdd00 | (((byte_offset) >> 1) & 0x00ff))

void asm_thumb_bgt_n(asm_thumb_t *as, int label) {
    int dest = get_label_dest(as, label);
    int rel = dest - as->code_offset;
    rel -= 4; // account for instruction prefetch, PC is 4 bytes ahead of this instruction
    if (SIGNED_FIT9(rel)) {
        asm_thumb_write_op16(as, OP_BGT_N(rel));
    } else {
        printf("asm_thumb_bgt: branch does not fit in 9 bits\n");
    }
}

void asm_thumb_mov_reg_i32(asm_thumb_t *as, uint reg_dest, machine_uint_t i32) {
    // movw, movt does it in 8 bytes
    // ldr [pc, #], dw does it in 6 bytes, but we might not reach to end of code for dw

    asm_thumb_mov_reg_i16(as, OP_MOVW, reg_dest, i32);
    asm_thumb_mov_reg_i16(as, OP_MOVT, reg_dest, i32 >> 16);
}

void asm_thumb_mov_reg_i32_optimised(asm_thumb_t *as, uint reg_dest, int i32) {
    if (reg_dest < 8 && UNSIGNED_FIT8(i32)) {
        asm_thumb_movs_rlo_i8(as, reg_dest, i32);
    } else if (UNSIGNED_FIT16(i32)) {
        asm_thumb_mov_reg_i16(as, OP_MOVW, reg_dest, i32);
    } else {
        asm_thumb_mov_reg_i32(as, reg_dest, i32);
    }
}

Damien's avatar
Damien committed
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
#define OP_STR_TO_SP_OFFSET(rlo_dest, word_offset) (0x9000 | ((rlo_dest) << 8) | ((word_offset) & 0x00ff))
#define OP_LDR_FROM_SP_OFFSET(rlo_dest, word_offset) (0x9800 | ((rlo_dest) << 8) | ((word_offset) & 0x00ff))

void asm_thumb_mov_local_reg(asm_thumb_t *as, int local_num, uint rlo_src) {
    assert(rlo_src < REG_R8);
    int word_offset = as->num_locals - local_num - 1;
    assert(as->pass < ASM_THUMB_PASS_3 || word_offset >= 0);
    asm_thumb_write_op16(as, OP_STR_TO_SP_OFFSET(rlo_src, word_offset));
}

void asm_thumb_mov_reg_local(asm_thumb_t *as, uint rlo_dest, int local_num) {
    assert(rlo_dest < REG_R8);
    int word_offset = as->num_locals - local_num - 1;
    assert(as->pass < ASM_THUMB_PASS_3 || word_offset >= 0);
    asm_thumb_write_op16(as, OP_LDR_FROM_SP_OFFSET(rlo_dest, word_offset));
}

void asm_thumb_mov_reg_local_addr(asm_thumb_t *as, uint reg_dest, int local_num) {
    assert(0);
    // see format 12, load address
    asm_thumb_write_op16(as, 0x0000);
}

#define OP_ADD_REG_REG_REG(rlo_dest, rlo_src_a, rlo_src_b) (0x1800 | ((rlo_src_b) << 6) | ((rlo_src_a) << 3) | (rlo_dest))

void asm_thumb_add_reg_reg_reg(asm_thumb_t *as, uint rlo_dest, uint rlo_src_a, uint rlo_src_b) {
    asm_thumb_write_op16(as, OP_ADD_REG_REG_REG(rlo_dest, rlo_src_a, rlo_src_b));
}

#define OP_CMP_REG_REG(rlo_a, rlo_b) (0x4280 | ((rlo_b) << 3) | (rlo_a))

void asm_thumb_cmp_reg_reg(asm_thumb_t *as, uint rlo_a, uint rlo_b) {
    asm_thumb_write_op16(as, OP_CMP_REG_REG(rlo_a, rlo_b));
}

void asm_thumb_ite_ge(asm_thumb_t *as) {
    asm_thumb_write_op16(as, 0xbfac);
}

#define OP_B(byte_offset) (0xe000 | (((byte_offset) >> 1) & 0x07ff))
// this could be wrong, because it should have a range of +/- 16MiB...
#define OP_BW_HI(byte_offset) (0xf000 | (((byte_offset) >> 12) & 0x07ff))
#define OP_BW_LO(byte_offset) (0xb800 | (((byte_offset) >> 1) & 0x07ff))

void asm_thumb_b_label(asm_thumb_t *as, int label) {
380
381
382
383
384
385
386
387
    int dest = get_label_dest(as, label);
    int rel = dest - as->code_offset;
    rel -= 4; // account for instruction prefetch, PC is 4 bytes ahead of this instruction
    if (dest >= 0 && rel <= -4) {
        // is a backwards jump, so we know the size of the jump on the first pass
        // calculate rel assuming 12 bit relative jump
        if (SIGNED_FIT12(rel)) {
            asm_thumb_write_op16(as, OP_B(rel));
Damien's avatar
Damien committed
388
        } else {
389
            goto large_jump;
Damien's avatar
Damien committed
390
        }
391
392
393
394
    } else {
        // is a forwards jump, so need to assume it's large
        large_jump:
        asm_thumb_write_op32(as, OP_BW_HI(rel), OP_BW_LO(rel));
Damien's avatar
Damien committed
395
396
397
398
399
400
401
402
403
404
405
406
    }
}

// all these bit arithmetics need coverage testing!
#define OP_BEQ(byte_offset) (0xd000 | (((byte_offset) >> 1) & 0x00ff))
#define OP_BEQW_HI(byte_offset) (0xf000 | (((byte_offset) >> 10) & 0x0400) | (((byte_offset) >> 14) & 0x003f))
#define OP_BEQW_LO(byte_offset) (0x8000 | ((byte_offset) & 0x2000) | (((byte_offset) >> 1) & 0x0fff))

void asm_thumb_cmp_reg_bz_label(asm_thumb_t *as, uint rlo, int label) {
    assert(rlo < REG_R8);

    // compare reg with 0
407
    asm_thumb_write_op16(as, OP_CMP_RLO_I8(rlo, 0));
Damien's avatar
Damien committed
408
409

    // branch if equal
410
411
412
413
414
    int dest = get_label_dest(as, label);
    int rel = dest - as->code_offset;
    rel -= 4; // account for instruction prefetch, PC is 4 bytes ahead of this instruction
    if (dest >= 0 && rel <= -4) {
        // is a backwards jump, so we know the size of the jump on the first pass
415
        // calculate rel assuming 9 bit relative jump
416
417
        if (SIGNED_FIT9(rel)) {
            asm_thumb_write_op16(as, OP_BEQ(rel));
Damien's avatar
Damien committed
418
        } else {
419
            goto large_jump;
Damien's avatar
Damien committed
420
        }
421
422
423
424
    } else {
        // is a forwards jump, so need to assume it's large
        large_jump:
        asm_thumb_write_op32(as, OP_BEQW_HI(rel), OP_BEQW_LO(rel));
Damien's avatar
Damien committed
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
    }
}

#define OP_BLX(reg) (0x4780 | ((reg) << 3))
#define OP_SVC(arg) (0xdf00 | (arg))
#define OP_LDR_FROM_BASE_OFFSET(rlo_dest, rlo_base, word_offset) (0x6800 | (((word_offset) << 6) & 0x07c0) | ((rlo_base) << 3) | (rlo_dest))

void asm_thumb_bl_ind(asm_thumb_t *as, void *fun_ptr, uint fun_id, uint reg_temp) {
    /* TODO make this use less bytes
    uint rlo_base = REG_R3;
    uint rlo_dest = REG_R7;
    uint word_offset = 4;
    asm_thumb_write_op16(as, 0x0000);
    asm_thumb_write_op16(as, 0x6800 | (word_offset << 6) | (rlo_base << 3) | rlo_dest); // ldr rlo_dest, [rlo_base, #offset]
    asm_thumb_write_op16(as, 0x4780 | (REG_R9 << 3)); // blx reg
    */

    if (0) {
        // load ptr to function into register using immediate, then branch
        // not relocatable
        asm_thumb_mov_reg_i32(as, reg_temp, (machine_uint_t)fun_ptr);
        asm_thumb_write_op16(as, OP_BLX(reg_temp));
    } else if (1) {
        asm_thumb_write_op16(as, OP_LDR_FROM_BASE_OFFSET(reg_temp, REG_R7, fun_id));
        asm_thumb_write_op16(as, OP_BLX(reg_temp));
    } else {
        // use SVC
        asm_thumb_write_op16(as, OP_SVC(fun_id));
    }
}