py/asmxtensa: Add low-level Xtensa assembler.

1 files changed, 170 insertions, 0 deletions

diff --git a/py/asmxtensa.c b/py/asmxtensa.c
new file mode 100644
index 0000000000..63aad02c06
--- /dev/null
+++ b/py/asmxtensa.c
@@ -0,0 +1,170 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <stdio.h>
+#include <assert.h>
+
+#include "py/mpconfig.h"
+
+// wrapper around everything in this file
+#if MICROPY_EMIT_XTENSA
+
+#include "py/asmxtensa.h"
+
+#define WORD_SIZE (4)
+#define SIGNED_FIT8(x) ((((x) & 0xffffff80) == 0) || (((x) & 0xffffff80) == 0xffffff80))
+#define SIGNED_FIT12(x) ((((x) & 0xfffff800) == 0) || (((x) & 0xfffff800) == 0xfffff800))
+
+void asm_xtensa_end_pass(asm_xtensa_t *as) {
+    as->num_const = as->cur_const;
+    as->cur_const = 0;
+
+    #if 0
+    // make a hex dump of the machine code
+    if (as->base.pass == MP_ASM_PASS_EMIT) {
+        uint8_t *d = as->base.code_base;
+        printf("XTENSA ASM:");
+        for (int i = 0; i < ((as->base.code_size + 15) & ~15); ++i) {
+            if (i % 16 == 0) {
+                printf("\n%08x:", (uint32_t)&d[i]);
+            }
+            if (i % 2 == 0) {
+                printf(" ");
+            }
+            printf("%02x", d[i]);
+        }
+        printf("\n");
+    }
+    #endif
+}
+
+void asm_xtensa_entry(asm_xtensa_t *as, int num_locals) {
+    // jump over the constants
+    asm_xtensa_op_j(as, as->num_const * WORD_SIZE + 4 - 4);
+    mp_asm_base_get_cur_to_write_bytes(&as->base, 1); // padding/alignment byte
+    as->const_table = (uint32_t*)mp_asm_base_get_cur_to_write_bytes(&as->base, as->num_const * 4);
+
+    // adjust the stack-pointer to store a0, a12, a13, a14 and locals, 16-byte aligned
+    as->stack_adjust = (((4 + num_locals) * WORD_SIZE) + 15) & ~15;
+    asm_xtensa_op_addi(as, ASM_XTENSA_REG_A1, ASM_XTENSA_REG_A1, -as->stack_adjust);
+
+    // save return value (a0) and callee-save registers (a12, a13, a14)
+    asm_xtensa_op_s32i_n(as, ASM_XTENSA_REG_A0, ASM_XTENSA_REG_A1, 0);
+    asm_xtensa_op_s32i_n(as, ASM_XTENSA_REG_A12, ASM_XTENSA_REG_A1, 1);
+    asm_xtensa_op_s32i_n(as, ASM_XTENSA_REG_A13, ASM_XTENSA_REG_A1, 2);
+    asm_xtensa_op_s32i_n(as, ASM_XTENSA_REG_A14, ASM_XTENSA_REG_A1, 3);
+}
+
+void asm_xtensa_exit(asm_xtensa_t *as) {
+    // restore registers
+    asm_xtensa_op_l32i_n(as, ASM_XTENSA_REG_A14, ASM_XTENSA_REG_A1, 3);
+    asm_xtensa_op_l32i_n(as, ASM_XTENSA_REG_A13, ASM_XTENSA_REG_A1, 2);
+    asm_xtensa_op_l32i_n(as, ASM_XTENSA_REG_A12, ASM_XTENSA_REG_A1, 1);
+    asm_xtensa_op_l32i_n(as, ASM_XTENSA_REG_A0, ASM_XTENSA_REG_A1, 0);
+
+    // restore stack-pointer and return
+    asm_xtensa_op_addi(as, ASM_XTENSA_REG_A1, ASM_XTENSA_REG_A1, as->stack_adjust);
+    asm_xtensa_op_ret_n(as);
+}
+
+STATIC uint32_t get_label_dest(asm_xtensa_t *as, uint label) {
+    assert(label < as->base.max_num_labels);
+    return as->base.label_offsets[label];
+}
+
+void asm_xtensa_op16(asm_xtensa_t *as, uint16_t op) {
+    uint8_t *c = mp_asm_base_get_cur_to_write_bytes(&as->base, 2);
+    c[0] = op;
+    c[1] = op >> 8;
+}
+
+void asm_xtensa_op24(asm_xtensa_t *as, uint32_t op) {
+    uint8_t *c = mp_asm_base_get_cur_to_write_bytes(&as->base, 3);
+    c[0] = op;
+    c[1] = op >> 8;
+    c[2] = op >> 16;
+}
+
+void asm_xtensa_j_label(asm_xtensa_t *as, uint label) {
+    uint32_t dest = get_label_dest(as, label);
+    int32_t rel = dest - as->base.code_offset - 4;
+    // we assume rel, as a signed int, fits in 18-bits
+    asm_xtensa_op_j(as, rel);
+}
+
+void asm_xtensa_bccz_reg_label(asm_xtensa_t *as, uint cond, uint reg, uint label) {
+    uint32_t dest = get_label_dest(as, label);
+    int32_t rel = dest - as->base.code_offset - 4;
+    if (as->base.pass == MP_ASM_PASS_EMIT && !SIGNED_FIT12(rel)) {
+        printf("ERROR: xtensa bccz out of range\n");
+    }
+    asm_xtensa_op_bccz(as, cond, reg, rel);
+}
+
+void asm_xtensa_bcc_reg_reg_label(asm_xtensa_t *as, uint cond, uint reg1, uint reg2, uint label) {
+    uint32_t dest = get_label_dest(as, label);
+    int32_t rel = dest - as->base.code_offset - 4;
+    if (as->base.pass == MP_ASM_PASS_EMIT && !SIGNED_FIT8(rel)) {
+        printf("ERROR: xtensa bcc out of range\n");
+    }
+    asm_xtensa_op_bcc(as, cond, reg1, reg2, rel);
+}
+
+// convenience function; reg_dest must be different from reg_src[12]
+void asm_xtensa_setcc_reg_reg_reg(asm_xtensa_t *as, uint cond, uint reg_dest, uint reg_src1, uint reg_src2) {
+    asm_xtensa_op_movi_n(as, reg_dest, 1);
+    asm_xtensa_op_bcc(as, cond, reg_src1, reg_src2, 1);
+    asm_xtensa_op_movi_n(as, reg_dest, 0);
+}
+
+void asm_xtensa_mov_reg_i32(asm_xtensa_t *as, uint reg_dest, uint32_t i32) {
+    if (SIGNED_FIT12(i32)) {
+        asm_xtensa_op_movi(as, reg_dest, i32);
+    } else {
+        // load the constant
+        asm_xtensa_op_l32r(as, reg_dest, as->base.code_offset, 4 + as->cur_const * WORD_SIZE);
+        // store the constant in the table
+        if (as->base.pass == MP_ASM_PASS_EMIT) {
+            as->const_table[as->cur_const] = i32;
+        }
+        ++as->cur_const;
+    }
+}
+
+void asm_xtensa_mov_local_reg(asm_xtensa_t *as, int local_num, uint reg_src) {
+    asm_xtensa_op_s32i(as, reg_src, ASM_XTENSA_REG_A1, 4 + local_num);
+}
+
+void asm_xtensa_mov_reg_local(asm_xtensa_t *as, uint reg_dest, int local_num) {
+    asm_xtensa_op_l32i(as, reg_dest, ASM_XTENSA_REG_A1, 4 + local_num);
+}
+
+void asm_xtensa_mov_reg_local_addr(asm_xtensa_t *as, uint reg_dest, int local_num) {
+    asm_xtensa_op_mov_n(as, reg_dest, ASM_XTENSA_REG_A1);
+    asm_xtensa_op_addi(as, reg_dest, reg_dest, (4 + local_num) * WORD_SIZE);
+}
+
+#endif // MICROPY_EMIT_XTENSA