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apple2a
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Make code even more compact.

This commit is contained in:
Lawrence Kesteloot 2018-08-05 12:06:45 -07:00
parent f33d9ed8bd
commit a6ed83d669
1 changed files with 64 additions and 54 deletions
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118
main.c
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@ -292,9 +292,10 @@ static uint8_t *skip_over(uint8_t *a, uint8_t *b) {
static void add_call(void *function) {
uint16_t addr = (uint16_t) function;
*g_c++ = I_JSR;
*g_c++ = addr & 0xFF;
*g_c++ = addr >> 8;
g_c[0] = I_JSR;
g_c[1] = addr & 0xFF;
g_c[2] = addr >> 8;
g_c += 3;
}
/**
@ -327,10 +328,11 @@ static uint16_t parse_uint16(uint8_t **s_ptr) {
* Generate code to put the value into AX.
*/
static void compile_load_ax(uint16_t value) {
*g_c++ = I_LDX_IMM;
*g_c++ = value >> 8;
*g_c++ = I_LDA_IMM;
*g_c++ = value & 0xFF;
g_c[0] = I_LDX_IMM;
g_c[1] = value >> 8;
g_c[2] = I_LDA_IMM;
g_c[3] = value & 0xFF;
g_c += 4;
}
/**
@ -512,10 +514,11 @@ static uint8_t *compile_expression(uint8_t *s) {
compile_load_ax(0);
} else {
// Load from var.
*g_c++ = I_LDA_ZPG;
*g_c++ = var;
*g_c++ = I_LDX_ZPG;
*g_c++ = var + 1;
g_c[0] = I_LDA_ZPG;
g_c[1] = var;
g_c[2] = I_LDX_ZPG;
g_c[3] = var + 1;
g_c += 4;
}
have_value_in_ax = 1;
} else {
@ -788,10 +791,11 @@ static void compile_buffer(uint8_t *buffer, uint16_t line_number) {
// Parse value.
s = compile_expression(s);
// Copy to var.
*g_c++ = I_STA_ZPG;
*g_c++ = var;
*g_c++ = I_STX_ZPG;
*g_c++ = var + 1;
g_c[0] = I_STA_ZPG;
g_c[1] = var;
g_c[2] = I_STX_ZPG;
g_c[3] = var + 1;
g_c += 4;
}
}
} else if (*s == T_HOME) {
@ -815,20 +819,22 @@ static void compile_buffer(uint8_t *buffer, uint16_t line_number) {
// Parse address.
s = compile_expression(s);
// Copy from AX to ptr1.
*g_c++ = I_STA_ZPG;
*g_c++ = (uint8_t) &ptr1;
*g_c++ = I_STX_ZPG;
*g_c++ = (uint8_t) &ptr1 + 1;
g_c[0] = I_STA_ZPG;
g_c[1] = (uint8_t) &ptr1;
g_c[2] = I_STX_ZPG;
g_c[3] = (uint8_t) &ptr1 + 1;
g_c += 4;
if (*s != ',') {
error = 1;
} else {
s++;
// Parse value. LSB is in A.
s = compile_expression(s);
*g_c++ = I_LDY_IMM; // Zero out Y.
*g_c++ = 0;
*g_c++ = I_STA_IND_Y; // Store at *ptr1.
*g_c++ = (uint8_t) &ptr1;
g_c[0] = I_LDY_IMM; // Zero out Y.
g_c[1] = 0;
g_c[2] = I_STA_IND_Y; // Store at *ptr1.
g_c[3] = (uint8_t) &ptr1;
g_c += 4;
}
} else if (*s == T_GOTO) {
s += 1;
@ -849,9 +855,10 @@ static void compile_buffer(uint8_t *buffer, uint16_t line_number) {
}
}
*g_c++ = I_JMP_ABS;
*g_c++ = addr & 0xFF;
*g_c++ = addr >> 8;
g_c[0] = I_JMP_ABS;
g_c[1] = addr & 0xFF;
g_c[2] = addr >> 8;
g_c += 3;
}
} else if (*s == T_IF) {
// Save where we are in case we need to roll back.
@ -861,18 +868,20 @@ static void compile_buffer(uint8_t *buffer, uint16_t line_number) {
// Parse conditional expression.
s = compile_expression(s);
// Check if AX is zero. Or the two bytes together, through the zero page.
*g_c++ = I_STX_ZPG;
*g_c++ = (uint8_t) &tmp1;
*g_c++ = I_ORA_ZPG;
*g_c++ = (uint8_t) &tmp1;
g_c[0] = I_STX_ZPG;
g_c[1] = (uint8_t) &tmp1;
g_c[2] = I_ORA_ZPG;
g_c[3] = (uint8_t) &tmp1;
// If so, skip to end of this line.
*g_c++ = I_BNE_REL;
*g_c++ = 3; // Skip over absolute jump.
*g_c++ = I_JMP_ABS;
g_c[4] = I_BNE_REL;
g_c[5] = 3; // Skip over absolute jump.
g_c[6] = I_JMP_ABS;
g_c += 7;
// TODO Check for overflow of end_of_line_address:
end_of_line_address[end_of_line_count++] = (uint8_t **) g_c;
*g_c++ = 0; // Address of next line.
*g_c++ = 0; // Address of next line.
g_c[0] = 0; // Address of next line.
g_c[1] = 0; // Address of next line.
g_c += 2;
if (*s == T_THEN) {
// Skip THEN and continue
@ -915,10 +924,11 @@ static void compile_buffer(uint8_t *buffer, uint16_t line_number) {
s = compile_expression(s);
// Copy to var.
*g_c++ = I_STA_ZPG;
*g_c++ = var;
*g_c++ = I_STX_ZPG;
*g_c++ = var + 1;
g_c[0] = I_STA_ZPG;
g_c[1] = var;
g_c[2] = I_STX_ZPG;
g_c[3] = var + 1;
g_c += 4;
if (*s == T_TO) {
s += 1;
@ -945,10 +955,9 @@ static void compile_buffer(uint8_t *buffer, uint16_t line_number) {
// there would mess up how we fill it in below. Inline
// it here so we have control over that.
loop_top_addr_addr = g_c;
*g_c++ = I_LDX_IMM;
g_c++;
*g_c++ = I_LDA_IMM;
g_c++;
g_c[0] = I_LDX_IMM;
g_c[2] = I_LDA_IMM;
g_c += 4;
add_call(for_statement);
error = 0;
@ -991,20 +1000,21 @@ static void compile_buffer(uint8_t *buffer, uint16_t line_number) {
// to if we're looping, or 0 if we're not.
// Copy from AX to ptr1. We must save it because checking it destroys it.
*g_c++ = I_STA_ZPG;
*g_c++ = (uint8_t) &ptr1;
*g_c++ = I_STX_ZPG;
*g_c++ = (uint8_t) &ptr1 + 1;
g_c[0] = I_STA_ZPG;
g_c[1] = (uint8_t) &ptr1;
g_c[2] = I_STX_ZPG;
g_c[3] = (uint8_t) &ptr1 + 1;
// Check if AX is zero. Destroys AX.
*g_c++ = I_ORA_ZPG;
*g_c++ = (uint8_t) &ptr1 + 1; // OR X into A.
g_c[4] = I_ORA_ZPG;
g_c[5] = (uint8_t) &ptr1 + 1; // OR X into A.
// If zero, skip over jump.
*g_c++ = I_BEQ_REL;
*g_c++ = 3; // Skip over indirect jump.
g_c[6] = I_BEQ_REL;
g_c[7] = 3; // Skip over indirect jump.
// Jump to top of loop, indirectly through ptr1, which has the address.
*g_c++ = I_JMP_IND;
*g_c++ = (uint8_t) &ptr1 & 0x0F;
*g_c++ = (uint8_t) &ptr1 >> 8;
g_c[8] = I_JMP_IND;
g_c[9] = (uint8_t) &ptr1 & 0x0F;
g_c[10] = (uint8_t) &ptr1 >> 8;
g_c += 11;
} else if (*s == T_GR) {
s += 1;
add_call(gr_statement);