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py/asmthumb: Extend asm entry/exit to handle stack larger than 508 bytes

This commit is contained in:
Damien George 2018-09-30 23:31:17 +10:00
parent ef9394e76a
commit 87231132d4
2 changed files with 19 additions and 2 deletions
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20
py/asmthumb.c
View File

@ -37,6 +37,7 @@
#include "py/asmthumb.h"
#define UNSIGNED_FIT5(x) ((uint32_t)(x) < 32)
#define UNSIGNED_FIT7(x) ((uint32_t)(x) < 128)
#define UNSIGNED_FIT8(x) (((x) & 0xffffff00) == 0)
#define UNSIGNED_FIT16(x) (((x) & 0xffff0000) == 0)
#define SIGNED_FIT8(x) (((x) & 0xffffff80) == 0) || (((x) & 0xffffff80) == 0xffffff80)
@ -44,6 +45,12 @@
#define SIGNED_FIT12(x) (((x) & 0xfffff800) == 0) || (((x) & 0xfffff800) == 0xfffff800)
#define SIGNED_FIT23(x) (((x) & 0xffc00000) == 0) || (((x) & 0xffc00000) == 0xffc00000)
// Note: these actually take an imm12 but the high-bit is not encoded here
#define OP_ADD_W_RRI_HI(reg_src) (0xf200 | (reg_src))
#define OP_ADD_W_RRI_LO(reg_dest, imm11) ((imm11 << 4 & 0x7000) | reg_dest << 8 | (imm11 & 0xff))
#define OP_SUB_W_RRI_HI(reg_src) (0xf2a0 | (reg_src))
#define OP_SUB_W_RRI_LO(reg_dest, imm11) ((imm11 << 4 & 0x7000) | reg_dest << 8 | (imm11 & 0xff))
#define OP_LDR_W_HI(reg_base) (0xf8d0 | (reg_base))
#define OP_LDR_W_LO(reg_dest, imm12) ((reg_dest) << 12 | (imm12))
@ -93,6 +100,7 @@ STATIC void asm_thumb_write_word32(asm_thumb_t *as, int w32) {
#define OP_POP_RLIST(rlolist) (0xbc00 | (rlolist))
#define OP_POP_RLIST_PC(rlolist) (0xbc00 | 0x0100 | (rlolist))
// The number of words must fit in 7 unsigned bits
#define OP_ADD_SP(num_words) (0xb000 | (num_words))
#define OP_SUB_SP(num_words) (0xb080 | (num_words))
@ -146,7 +154,11 @@ void asm_thumb_entry(asm_thumb_t *as, int num_locals) {
}
asm_thumb_op16(as, OP_PUSH_RLIST_LR(reglist));
if (stack_adjust > 0) {
asm_thumb_op16(as, OP_SUB_SP(stack_adjust));
if (UNSIGNED_FIT7(stack_adjust)) {
asm_thumb_op16(as, OP_SUB_SP(stack_adjust));
} else {
asm_thumb_op32(as, OP_SUB_W_RRI_HI(ASM_THUMB_REG_SP), OP_SUB_W_RRI_LO(ASM_THUMB_REG_SP, stack_adjust * 4));
}
}
as->push_reglist = reglist;
as->stack_adjust = stack_adjust;
@ -154,7 +166,11 @@ void asm_thumb_entry(asm_thumb_t *as, int num_locals) {
void asm_thumb_exit(asm_thumb_t *as) {
if (as->stack_adjust > 0) {
asm_thumb_op16(as, OP_ADD_SP(as->stack_adjust));
if (UNSIGNED_FIT7(as->stack_adjust)) {
asm_thumb_op16(as, OP_ADD_SP(as->stack_adjust));
} else {
asm_thumb_op32(as, OP_ADD_W_RRI_HI(ASM_THUMB_REG_SP), OP_ADD_W_RRI_LO(ASM_THUMB_REG_SP, as->stack_adjust * 4));
}
}
asm_thumb_op16(as, OP_POP_RLIST_PC(as->push_reglist));
}

1
py/asmthumb.h
View File

@ -46,6 +46,7 @@
#define ASM_THUMB_REG_R13 (13)
#define ASM_THUMB_REG_R14 (14)
#define ASM_THUMB_REG_R15 (15)
#define ASM_THUMB_REG_SP (ASM_THUMB_REG_R13)
#define ASM_THUMB_REG_LR (REG_R14)
#define ASM_THUMB_CC_EQ (0x0)