From 87231132d451e7413dbb97cae74d89721c41634b Mon Sep 17 00:00:00 2001 From: Damien George Date: Sun, 30 Sep 2018 23:31:17 +1000 Subject: [PATCH] py/asmthumb: Extend asm entry/exit to handle stack larger than 508 bytes --- py/asmthumb.c | 20 ++++++++++++++++++-- py/asmthumb.h | 1 + 2 files changed, 19 insertions(+), 2 deletions(-) diff --git a/py/asmthumb.c b/py/asmthumb.c index f86cc101e..54b539a8d 100644 --- a/py/asmthumb.c +++ b/py/asmthumb.c @@ -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)); } diff --git a/py/asmthumb.h b/py/asmthumb.h index eabbc59a9..83aec0287 100644 --- a/py/asmthumb.h +++ b/py/asmthumb.h @@ -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)